path: root/help/genius.txt

Genius Manual

Jiř Lebl

   Oklahoma State University

    <jirka@5z.com>

Kai Willadsen

   University of Queensland, Australia

    <kaiw@itee.uq.edu.au>

   Copyright © 1997-2016 Jiř (George) Lebl

   Copyright © 2004 Kai Willadsen

   Manual for the Genius Math Tool.

   Permission is granted to copy, distribute and/or modify this
   document under the terms of the GNU Free Documentation License
   (GFDL), Version 1.1 or any later version published by the Free
   Software Foundation with no Invariant Sections, no Front-Cover
   Texts, and no Back-Cover Texts. You can find a copy of the GFDL
   at this link or in the file COPYING-DOCS distributed with this
   manual.

   This manual is part of a collection of GNOME manuals
   distributed under the GFDL. If you want to distribute this
   manual separately from the collection, you can do so by adding
   a copy of the license to the manual, as described in section 6
   of the license.

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   then the names are in capital letters or initial capital
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   DOCUMENT AND MODIFIED VERSIONS OF THE DOCUMENT ARE PROVIDED
   UNDER THE TERMS OF THE GNU FREE DOCUMENTATION LICENSE WITH THE
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       OF THE POSSIBILITY OF SUCH DAMAGES.

   Feedback

   To report a bug or make a suggestion regarding the Genius
   Mathematics Tool application or this manual, please visit the
   Genius Web page or email me at <jirka@5z.com>.
     __________________________________________________________

   Table of Contents
   1. Introduction
   2. Getting Started

        2.1. To Start Genius Mathematics Tool
        2.2. When You Start Genius

   3. Basic Usage

        3.1. Using the Work Area
        3.2. To Create a New Program
        3.3. To Open and Run a Program

   4. Plotting

        4.1. Line Plots
        4.2. Parametric Plots
        4.3. Slopefield Plots
        4.4. Vectorfield Plots
        4.5. Surface Plots

   5. GEL Basics

        5.1. Values

              5.1.1. Numbers
              5.1.2. Booleans
              5.1.3. Strings
              5.1.4. Null

        5.2. Using Variables

              5.2.1. Setting Variables
              5.2.2. Built-in Variables
              5.2.3. Previous Result Variable

        5.3. Using Functions

              5.3.1. Defining Functions
              5.3.2. Variable Argument Lists
              5.3.3. Passing Functions to Functions
              5.3.4. Operations on Functions

        5.4. Separator
        5.5. Comments
        5.6. Modular Evaluation
        5.7. List of GEL Operators

   6. Programming with GEL

        6.1. Conditionals
        6.2. Loops

              6.2.1. While Loops
              6.2.2. For Loops
              6.2.3. Foreach Loops
              6.2.4. Break and Continue

        6.3. Sums and Products
        6.4. Comparison Operators
        6.5. Global Variables and Scope of Variables
        6.6. Parameter variables
        6.7. Returning
        6.8. References
        6.9. Lvalues

   7. Advanced Programming with GEL

        7.1. Error Handling
        7.2. Toplevel Syntax
        7.3. Returning Functions
        7.4. True Local Variables
        7.5. GEL Startup Procedure
        7.6. Loading Programs

   8. Matrices in GEL

        8.1. Entering Matrices
        8.2. Conjugate Transpose and Transpose Operator
        8.3. Linear Algebra

   9. Polynomials in GEL

        9.1. Using Polynomials

   10. Set Theory in GEL

        10.1. Using Sets

   11. List of GEL functions

        11.1. Commands
        11.2. Basic
        11.3. Parameters
        11.4. Constants
        11.5. Numeric
        11.6. Trigonometry
        11.7. Number Theory
        11.8. Matrix Manipulation
        11.9. Linear Algebra
        11.10. Combinatorics
        11.11. Calculus
        11.12. Functions
        11.13. Equation Solving
        11.14. Statistics
        11.15. Polynomials
        11.16. Set Theory
        11.17. Commutative Algebra
        11.18. Miscellaneous
        11.19. Symbolic Operations
        11.20. Plotting

   12. Example Programs in GEL
   13. Settings

        13.1. Output
        13.2. Precision
        13.3. Terminal
        13.4. Memory

   14. About Genius Mathematics Tool

   List of Figures
   2-1. Genius Mathematics Tool Window
   4-1. Create Plot Window
   4-2. Plot Window
   4-3. Parametric Plot Tab
   4-4. Parametric Plot
   4-5. Surface Plot
     __________________________________________________________

Chapter 1. Introduction

   The Genius Mathematics Tool application is a general calculator
   for use as a desktop calculator, an educational tool in
   mathematics, and is useful even for research. The language used
   in Genius Mathematics Tool is designed to be ‘mathematical’ in
   the sense that it should be ‘what you mean is what you get’. Of
   course that is not an entirely attainable goal. Genius
   Mathematics Tool features rationals, arbitrary precision
   integers and multiple precision floats using the GMP library.
   It handles complex numbers using cartesian notation. It has
   good vector and matrix manipulation and can handle basic linear
   algebra. The programming language allows user defined
   functions, variables and modification of parameters.

   Genius Mathematics Tool comes in two versions. One version is
   the graphical GNOME version, which features an IDE style
   interface and the ability to plot functions of one or two
   variables. The command line version does not require GNOME, but
   of course does not implement any feature that requires the
   graphical interface.

   Parts of this manual describe the graphical version of the
   calculator, but the language is of course the same. The command
   line only version lacks the graphing capabilities and all other
   capabilities that require the graphical user interface.

   Generally, when some feature of the language (function,
   operator, etc...) is new in some version past 1.0.5, it is
   mentioned, but below 1.0.5 you would have to look at the NEWS
   file.
     __________________________________________________________

Chapter 2. Getting Started

2.1. To Start Genius Mathematics Tool

   You can start Genius Mathematics Tool in the following ways:

   Applications menu
          Depending on your operating system and version, the menu
          item for Genius Mathematics Tool could appear in a
          number of different places. It can be in the Education,
          Accessories, Office, Science, or similar submenu,
          depending on your particular setup. The menu item name
          you are looking for is Genius Math Tool. Once you locate
          this menu item click on it to start Genius Mathematics
          Tool.

   Run dialog
          Depending on your system installation the menu item may
          not be available. If it is not, you can open the Run
          dialog and execute gnome-genius.

   Command line
          To start the GNOME version of Genius Mathematics Tool
          execute gnome-genius from the command line.

          To start the command line only version, execute the
          following command: genius. This version does not include
          the graphical environment and some functionality such as
          plotting will not be available.
     __________________________________________________________

2.2. When You Start Genius

   When you start the GNOME edition of Genius Mathematics Tool,
   the window pictured in Figure 2-1 is displayed.

   Figure 2-1. Genius Mathematics Tool Window

   [genius_window.png]

   The Genius Mathematics Tool window contains the following
   elements:

   Menubar.
          The menus on the menubar contain all of the commands
          that you need to work with files in Genius Mathematics
          Tool. The File menu contains items for loading and
          saving items and creating new programs. The Load and
          Run... command does not open a new window for the
          program, but just executes the program directly. It is
          equivalent to the load command.

          The Calculator menu controls the calculator engine. It
          allows you to run the currently selected program or to
          interrupt the current calculation. You can also look at
          the full expression of the last answer (useful if the
          last answer was too large to fit onto the console), or
          you can view a listing of the values of all user defined
          variables. You can also monitor user variables, which is
          especially useful while a long calculation is running,
          or to debug a certain program. Finally the Calculator
          allows plotting functions using a user friendly dialog
          box.

          The Examples menu is a list of example programs or
          demos. If you open the menu, it will load the example
          into a new program, which you can run, edit, modify, and
          save. These programs should be well documented and
          generally demonstrate either some feature of Genius
          Mathematics Tool or some mathematical concept.

          The Programs menu lists the currently open programs and
          allows you to switch between them.

          The other menus have same familiar functions as in other
          applications.

   Toolbar.
          The toolbar contains a subset of the commands that you
          can access from the menubar.

   Working area
          The working area is the primary method of interacting
          with the application.

          The working area initially has just the Console tab,
          which is the main way of interacting with the
          calculator. Here you type expressions and the results
          are immediately returned after you hit the Enter key.

          Alternatively you can write longer programs and those
          can appear in separate tabs. The programs are a set of
          commands or functions that can be run all at once rather
          than entering them at the command line. The programs can
          be saved in files for later retrieval.
     __________________________________________________________

Chapter 3. Basic Usage

3.1. Using the Work Area

   Normally you interact with the calculator in the Console tab of
   the work area. If you are running the text only version then
   the console will be the only thing that is available to you. If
   you want to use Genius Mathematics Tool as a calculator only,
   just type in your expression in the console, it will be
   evaluated, and the returned value will be printed.

   To evaluate an expression, type it into the Console work area
   and press enter. Expressions are written in a language called
   GEL. The most simple GEL expressions just looks like
   mathematics. For example
genius> 30*70 + 67^3.0 + ln(7) * (88.8/100)

   or
genius> 62734 + 812634 + 77^4 mod 5

   or
genius> | sin(37) - e^7 |

   or
genius> sum n=1 to 70 do 1/n

   (Last is the harmonic sum from 1 to 70)

   To get a list of functions and commands, type:
genius> help

   If you wish to get more help on a specific function, type:
genius> help FunctionName

   To view this manual, type:
genius> manual

   Suppose you have previously saved some GEL commands as a
   program to a file and you now want to execute them. To load
   this program from the file path/to/program.gel, type
genius> load path/to/program.gel

   Genius Mathematics Tool keeps track of the current directory.
   To list files in the current directory type ls, to change
   directory do cd directory as in the UNIX command shell.
     __________________________________________________________

3.2. To Create a New Program

   If you wish to enter several more complicated commands, or
   perhaps write a complicated function using the GEL language,
   you can create a new program.

   To start writing a new program, choose File->New Program. A new
   tab will appear in the work area. You can write a GEL program
   in this work area. Once you have written your program you can
   run it by Calculator->Run (or the Run toolbar button). This
   will execute your program and will display any output on the
   Console tab. Executing a program is equivalent of taking the
   text of the program and typing it into the console. The only
   difference is that this input is done independent of the
   console and just the output goes onto the console.
   Calculator->Run will always run the currently selected program
   even if you are on the Console tab. The currently selected
   program has its tab in bold type. To select a program, just
   click on its tab.

   To save the program you've just written, choose File->Save
   As.... Similarly as in other programs you can choose File->Save
   to save a program that already has a filename attached to it.
   If you have many opened programs you have edited and wish to
   save you can also choose File->Save All Unsaved.

   Programs that have unsaved changes will have a "[+]" next to
   their filename. This way you can see if the file on disk and
   the currently opened tab differ in content. Programs which have
   not yet had a filename associated with them are always
   considered unsaved and no "[+]" is printed.
     __________________________________________________________

3.3. To Open and Run a Program

   To open a file, choose File->Open. A new tab containing the
   file will appear in the work area. You can use this to edit the
   file.

   To run a program from a file, choose File->Load and Run....
   This will run the program without opening it in a separate tab.
   This is equivalent to the load command.

   If you have made edits to a file you wish to throw away and
   want to reload to the version that's on disk, you can choose
   the File->Reload from Disk menuitem. This is useful for
   experimenting with a program and making temporary edits, to run
   a program, but that you do not intend to keep.
     __________________________________________________________

Chapter 4. Plotting

   Plotting support is only available in the graphical GNOME
   version. All plotting accessible from the graphical interface
   is available from the Create Plot window. You can access this
   window by either clicking on the Plot button on the toolbar or
   selecting Plot from the Calculator menu. You can also access
   the plotting functionality by using the plotting functions of
   the GEL language. See Chapter 5 to find out how to enter
   expressions that Genius understands.
     __________________________________________________________

4.1. Line Plots

   To graph real valued functions of one variable open the Create
   Plot window. You can also use the LinePlot function on the
   command line (see its documentation).

   Once you click the Plot button, a window opens up with some
   notebooks in it. You want to be in the Function line plot
   notebook tab, and inside you want to be on the Functions /
   Expressions notebook tab. See Figure 4-1.

   Figure 4-1. Create Plot Window

   [line_plot.png]

   Type expressions with x as the independent variable into the
   textboxes. Alternatively you can give names of functions such
   as cos rather then having to type cos(x). You can graph up to
   ten functions. If you make a mistake and Genius cannot parse
   the input it will signify this with a warning icon on the right
   of the text input box where the error occurred, as well as
   giving you an error dialog. You can change the ranges of the
   dependent and independent variables in the bottom part of the
   dialog. The y (dependent) range can be set automatically by
   turning on the Fit dependent axis checkbox. The names of the
   variables can also be changed. Pressing the Plot button
   produces the graph shown in Figure 4-2.

   The variables can be renamed by clicking the Change variable
   names... button, which is useful if you wish to print or save
   the figure and don't want to use the standard names. Finally
   you can also avoid printing the legend and the axis labels
   completely, which is also useful if printing or saving, when
   the legend might simply be clutter.

   Figure 4-2. Plot Window

   [line_plot_graph.png]

   From here you can print out the plot, create encapsulated
   postscript or a PNG version of the plot or change the zoom. If
   the dependent axis was not set correctly you can have Genius
   fit it by finding out the extrema of the graphed functions.

   For plotting using the command line see the documentation of
   the LinePlot function.
     __________________________________________________________

4.2. Parametric Plots

   In the create plot window, you can also choose the Parametric
   notebook tab to create two dimensional parametric plots. This
   way you can plot a single parametric function. You can either
   specify the points as x and y, or giving a single complex
   number as a function of the variable t. The range of the
   variable t is given explicitly, and the function is sampled
   according to the given increment. The x and y range can be set
   automatically by turning on the Fit dependent axis checkbox, or
   it can be specified explicitly. See Figure 4-3.

   Figure 4-3. Parametric Plot Tab

   [parametric.png]

   An example of a parametric plot is given in Figure 4-4. Similar
   operations can be done on such graphs as can be done on the
   other line plots. For plotting using the command line see the
   documentation of the LinePlotParametric or LinePlotCParametric
   function.

   Figure 4-4. Parametric Plot

   [parametric_graph.png]
     __________________________________________________________

4.3. Slopefield Plots

   In the create plot window, you can also choose the Slope field
   notebook tab to create a two dimensional slope field plot.
   Similar operations can be done on such graphs as can be done on
   the other line plots. For plotting using the command line see
   the documentation of the SlopefieldPlot function.

   When a slope field is active, there is an extra Solver menu
   available, through which you can bring up the solver dialog.
   Here you can have Genius plot specific solutions for the given
   initial conditions. You can either specify initial conditions
   in the dialog, or you can click on the plot directly to specify
   the initial point. While the solver dialog is active, the
   zooming by clicking and dragging does not work. You have to
   close the dialog first if you want to zoom using the mouse.

   The solver uses the standard Runge-Kutta method. The plots will
   stay on the screen until cleared. The solver will stop whenever
   it reaches the boundary of the plot window. Zooming does not
   change the limits or parameters of the solutions, you will have
   to clear and redraw them with appropriate parameters. You can
   also use the SlopefieldDrawSolution function to draw solutions
   from the command line or programs.
     __________________________________________________________

4.4. Vectorfield Plots

   In the create plot window, you can also choose the Vector field
   notebook tab to create a two dimensional vector field plot.
   Similar operations can be done on such graphs as can be done on
   the other line plots. For plotting using the command line see
   the documentation of the VectorfieldPlot function.

   By default the direction and magnitude of the vector field is
   shown. To only show direction and not the magnitude, check the
   appropriate checkbox to normalize the arrow lengths.

   When a vector field is active, there is an extra Solver menu
   available, through which you can bring up the solver dialog.
   Here you can have Genius plot specific solutions for the given
   initial conditions. You can either specify initial conditions
   in the dialog, or you can click on the plot directly to specify
   the initial point. While the solver dialog is active, the
   zooming by clicking and dragging does not work. You have to
   close the dialog first if you want to zoom using the mouse.

   The solver uses the standard Runge-Kutta method. The plots will
   stay on the screen until cleared. Zooming does not change the
   limits or parameters of the solutions, you will have to clear
   and redraw them with appropriate parameters. You can also use
   the VectorfieldDrawSolution function to draw solutions from the
   command line or programs.
     __________________________________________________________

4.5. Surface Plots

   Genius can also plot surfaces. Select the Surface plot tab in
   the main notebook of the Create Plot window. Here you can
   specify a single expression that should use either x and y as
   real independent variables or z as a complex variable (where x
   is the real part of z and y is the imaginary part). For example
   to plot the modulus of the cosine function for complex
   parameters, you could enter |cos(z)|. This would be equivalent
   to |cos(x+1i*y)|. See Figure 4-5. For plotting using the
   command line see the documentation of the SurfacePlot function.

   The z range can be set automatically by turning on the Fit
   dependent axis checkbox. The variables can be renamed by
   clicking the Change variable names... button, which is useful
   if you wish to print or save the figure and don't want to use
   the standard names. Finally you can also avoid printing the
   legend, which is also useful if printing or saving, when the
   legend might simply be clutter.

   Figure 4-5. Surface Plot

   [surface_graph.png]

   In surface mode, left and right arrow keys on your keyboard
   will rotate the view along the z axis. Alternatively you can
   rotate along any axis by selecting Rotate axis... in the View
   menu. The View menu also has a top view mode which rotates the
   graph so that the z axis is facing straight out, that is, we
   view the graph from the top and get essentially just the colors
   that define the values of the function getting a temperature
   plot of the function. Finally you should try Start rotate
   animation, to start a continuous slow rotation. This is
   especially good if using Genius Mathematics Tool to present to
   an audience.
     __________________________________________________________

Chapter 5. GEL Basics

   GEL stands for Genius Extension Language. It is the language
   you use to write programs in Genius. A program in GEL is simply
   an expression that evaluates to a number, a matrix, or another
   object in GEL. Genius Mathematics Tool can be used as a simple
   calculator, or as a powerful theoretical research tool. The
   syntax is meant to have as shallow of a learning curve as
   possible, especially for use as a calculator.
     __________________________________________________________

5.1. Values

   Values in GEL can be numbers, Booleans, or strings. GEL also
   treats matrices as values. Values can be used in calculations,
   assigned to variables and returned from functions, among other
   uses.
     __________________________________________________________

5.1.1. Numbers

   Integers are the first type of number in GEL. Integers are
   written in the normal way.
1234

   Hexadecimal and octal numbers can be written using C notation.
   For example:
0x123ABC
01234

   Or you can type numbers in an arbitrary base using
   <base>\<number>. Digits higher than 10 use letters in a similar
   way to hexadecimal. For example, a number in base 23 could be
   written:
23\1234ABCD

   The second type of GEL number is rationals. Rationals are
   simply achieved by dividing two integers. So one could write:
3/4

   to get three quarters. Rationals also accept mixed fraction
   notation. So in order to get one and three tenths you could
   write:
1 3/10

   The next type of number is floating point. These are entered in
   a similar fashion to C notation. You can use E, e or @ as the
   exponent delimiter. Note that using the exponent delimiter
   gives a float even if there is no decimal point in the number.
   Examples:
1.315
7.887e77
7.887e-77
.3
0.3
77e5

   When Genius prints a floating point number it will always
   append a .0 even if the number is whole. This is to indicate
   that floating point numbers are taken as imprecise quantities.
   When a number is written in the scientific notation, it is
   always a floating point number and thus Genius does not print
   the .0.

   The final type of number in GEL is the complex numbers. You can
   enter a complex number as a sum of real and imaginary parts. To
   add an imaginary part, append an i. Here are examples of
   entering complex numbers:
1+2i
8.01i
77*e^(1.3i)

   Important

   When entering imaginary numbers, a number must be in front of
   the i. If you use i by itself, Genius will interpret this as
   referring to the variable i. If you need to refer to i by
   itself, use 1i instead.

   In order to use mixed fraction notation with imaginary numbers
   you must have the mixed fraction in parentheses. (i.e., (1
   2/5)i)
     __________________________________________________________

5.1.2. Booleans

   Genius also supports native Boolean values. The two Boolean
   constants are defined as true and false; these identifiers can
   be used like any other variable. You can also use the
   identifiers True, TRUE, False and FALSE as aliases for the
   above.

   At any place where a Boolean expression is expected, you can
   use a Boolean value or any expression that produces either a
   number or a Boolean. If Genius needs to evaluate a number as a
   Boolean it will interpret 0 as false and any other number as
   true.

   In addition, you can do arithmetic with Boolean values. For
   example:
( (1 + true) - false ) * true

   is the same as:
( (true or true) or not false ) and true

   Only addition, subtraction and multiplication are supported. If
   you mix numbers with Booleans in an expression then the numbers
   are converted to Booleans as described above. This means that,
   for example:
1 == true

   always evaluates to true since 1 will be converted to true
   before being compared to true.
     __________________________________________________________

5.1.3. Strings

   Like numbers and Booleans, strings in GEL can be stored as
   values inside variables and passed to functions. You can also
   concatenate a string with another value using the plus
   operator. For example:
a=2+3;"The result is: "+a

   will create the string:
The result is: 5

   You can also use C-like escape sequences such as \n,\t,\b,\a
   and \r. To get a \ or " into the string you can quote it with a
   \. For example:
"Slash: \\ Quotes: \" Tabs: \t1\t2\t3"

   will make a string:
Slash: \ Quotes: " Tabs:        1       2       3

   Do note however that when a string is returned from a function,
   escapes are quoted, so that the output can be used as input. If
   you wish to print the string as it is (without escapes), use
   the print or printn functions.

   In addition, you can use the library function string to convert
   anything to a string. For example:
string(22)

   will return
"22"

   Strings can also be compared with == (equal), != (not equal)
   and <=> (comparison) operators
     __________________________________________________________

5.1.4. Null

   There is a special value called null. No operations can be
   performed on it, and nothing is printed when it is returned.
   Therefore, null is useful when you do not want output from an
   expression. The value null can be obtained as an expression
   when you type ., the constant null or nothing. By nothing we
   mean that if you end an expression with a separator ;, it is
   equivalent to ending it with a separator followed by a null.

   Example:
x=5;.
x=5;

   Some functions return null when no value can be returned or an
   error happened. Also null is used as an empty vector or matrix,
   or an empty reference.
     __________________________________________________________

5.2. Using Variables

   Syntax:
VariableName

   Example:
genius> e
= 2.71828182846

   To evaluate a variable by itself, just enter the name of the
   variable. This will return the value of the variable. You can
   use a variable anywhere you would normally use a number or
   string. In addition, variables are necessary when defining
   functions that take arguments (see Section 5.3.1).

   Tip Using Tab completion


   You can use Tab completion to get Genius to complete variable
   names for you. Try typing the first few letters of the name and
   pressing Tab.

   Important Variable names are case sensitive


   The names of variables are case sensitive. That means that
   variables named hello, HELLO and Hello are all different
   variables.
     __________________________________________________________

5.2.1. Setting Variables

   Syntax:
<identifier> = <value>
<identifier> := <value>

   Example:
x = 3
x := 3

   To assign a value to a variable, use the = or := operators.
   These operators set the value of the variable and return the
   value you set, so you can do things like
a = b = 5

   This will set b to 5 and then also set a to 5.

   The = and := operators can both be used to set variables. The
   difference between them is that the := operator always acts as
   an assignment operator, whereas the = operator may be
   interpreted as testing for equality when used in a context
   where a Boolean expression is expected.

   For more information about the scope of variables, that is when
   are what variables visible, see Section 6.5.
     __________________________________________________________

5.2.2. Built-in Variables

   GEL has a number of built-in ‘variables’, such as e, pi or
   GoldenRatio. These are widely used constants with a preset
   value, and they cannot be assigned new values. There are a
   number of other built-in variables. See Section 11.4 for a full
   list. Note that i is not by default the square root of negative
   one (the imaginary number), and is undefined to allow its use
   as a counter. If you wish to write the imaginary number you
   need to use 1i.
     __________________________________________________________

5.2.3. Previous Result Variable

   The Ans and ans variables can be used to get the result of the
   last expression. For example, if you had performed some
   calculation, to add 389 to the result you could do:
Ans+389
     __________________________________________________________

5.3. Using Functions

   Syntax:
FunctionName(argument1, argument2, ...)

   Example:
Factorial(5)
cos(2*pi)
gcd(921,317)

   To evaluate a function, enter the name of the function,
   followed by the arguments (if any) to the function in
   parentheses. This will return the result of applying the
   function to its arguments. The number of arguments to the
   function is, of course, different for each function.

   There are many built-in functions, such as sin, cos and tan.
   You can use the help built-in command to get a list of
   available functions, or see Chapter 11 for a full listing.

   Tip Using Tab completion


   You can use Tab completion to get Genius to complete function
   names for you. Try typing the first few letters of the name and
   pressing Tab.

   Important Function names are case sensitive


   The names of functions are case sensitive. That means that
   functions named dosomething, DOSOMETHING and DoSomething are
   all different functions.
     __________________________________________________________

5.3.1. Defining Functions

   Syntax:
function <identifier>(<comma separated arguments>) = <function body>
<identifier> = (`() = <function body>)

   The ` is the backquote character, and signifies an anonymous
   function. By setting it to a variable name you effectively
   define a function.

   A function takes zero or more comma separated arguments, and
   returns the result of the function body. Defining your own
   functions is primarily a matter of convenience; one possible
   use is to have sets of functions defined in GEL files that
   Genius can load in order to make them available. Example:
function addup(a,b,c) = a+b+c

   then addup(1,4,9) yields 14
     __________________________________________________________

5.3.2. Variable Argument Lists

   If you include ... after the last argument name in the function
   declaration, then Genius will allow any number of arguments to
   be passed in place of that argument. If no arguments were
   passed then that argument will be set to null. Otherwise, it
   will be a horizontal vector containing all the arguments. For
   example:
function f(a,b...) = b

   Then f(1,2,3) yields [2,3], while f(1) yields a null.
     __________________________________________________________

5.3.3. Passing Functions to Functions

   In Genius, it is possible to pass a function as an argument to
   another function. This can be done using either ‘function
   nodes’ or anonymous functions.

   If you do not enter the parentheses after a function name,
   instead of being evaluated, the function will instead be
   returned as a ‘function node’. The function node can then be
   passed to another function. Example:
function f(a,b) = a(b)+1;
function b(x) = x*x;
f(b,2)

   To pass functions that are not defined, you can use an
   anonymous function (see Section 5.3.1). That is, you want to
   pass a function without giving it a name. Syntax:
function(<comma separated arguments>) = <function body>
`(<comma separated arguments>) = <function body>

   Example:
function f(a,b) = a(b)+1;
f(`(x) = x*x,2)

   This will return 5.
     __________________________________________________________

5.3.4. Operations on Functions

   Some functions allow arithmetic operations, and some single
   argument functions such as exp or ln, to operate on the
   function. For example,
exp(sin*cos+4)

   will return a function that takes x and returns
   exp(sin(x)*cos(x)+4). It is functionally equivalent to typing
`(x) = exp(sin(x)*cos(x)+4)

   This operation can be useful when quickly defining functions.
   For example to create a function called f to perform the above
   operation, you can just type:
f = exp(sin*cos+4)

   It can also be used in plotting. For example, to plot sin
   squared you can enter:
LinePlot(sin^2)

   Warning

   Not all functions can be used in this way. For example, when
   you use a binary operation the functions must take the same
   number of arguments.
     __________________________________________________________

5.4. Separator

   GEL is somewhat different from other languages in how it deals
   with multiple commands and functions. In GEL you must chain
   commands together with a separator operator. That is, if you
   want to type more than one expression you have to use the ;
   operator in between the expressions. This is a way in which
   both expressions are evaluated and the result of the second one
   (or the last one if there is more than two expressions) is
   returned. Suppose you type the following:
3 ; 5

   This expression will yield 5.

   This will require some parenthesizing to make it unambiguous
   sometimes, especially if the ; is not the top most primitive.
   This slightly differs from other programming languages where
   the ; is a terminator of statements, whereas in GEL it’s
   actually a binary operator. If you are familiar with pascal
   this should be second nature. However genius can let you
   pretend it is a terminator to some degree. If a ; is found at
   the end of a parenthesis or a block, genius will append a null
   to it as if you would have written ;null. This is useful in
   case you do not want to return a value from say a loop, or if
   you handle the return differently. Note that it will slightly
   slow down the code if it is executed too often as there is one
   more operator involved.

   If you are typing expressions in a program you do not have to
   add a semicolon. In this case genius will simply print the
   return value whenever it executes the expression. However, do
   note that if you are defining a function, the body of the
   function is a single expression.
     __________________________________________________________

5.5. Comments

   GEL is similar to other scripting languages in that # denotes a
   comment, that is text that is not meant to be evaluated.
   Everything beyond the pound sign till the end of line will just
   be ignored. For example,
# This is just a comment
# every line in a comment must have its own pound sign
# in the next line we set x to the value 123
x=123;
     __________________________________________________________

5.6. Modular Evaluation

   Genius implements modular arithmetic. To use it you just add
   "mod <integer>" after the expression. Example: 2^(5!) * 3^(6!)
   mod 5 It could be possible to do modular arithmetic by
   computing with integers and then modding in the end with the %
   operator, which simply gives the remainder, but that may be
   time consuming if not impossible when working with larger
   numbers. For example, 10^(10^10) % 6 will simply not work (the
   exponent will be too large), while 10^(10^10) mod 6 is
   instantaneous. The first expression first tries to compute the
   integer 10^(10^10) and then find remainder after division by 6,
   while the second expression evaluates everything modulo 6 to
   begin with.

   You can calculate the inverses of numbers mod some integer by
   just using rational numbers (of course the inverse has to
   exist). Examples:
10^-1 mod 101
1/10 mod 101

   You can also do modular evaluation with matrices including
   taking inverses, powers and dividing. Example:
A = [1,2;3,4]
B = A^-1 mod 5
A*B mod 5

   This should yield the identity matrix as B will be the inverse
   of A mod 5.

   Some functions such as sqrt or log work in a different way when
   in modulo mode. These will then work like their discrete
   versions working within the ring of integers you selected. For
   example:
genius> sqrt(4) mod 7
=
[2, 5]
genius> 2*2 mod 7
= 4

   sqrt will actually return all the possible square roots.

   Do not chain mod operators, simply place it at the end of the
   computation, all computations in the expression on the left
   will be carried out in mod arithmetic. If you place a mod
   inside a mod, you will get unexpected results. If you simply
   want to mod a single number and control exactly when remainders
   are taken, best to use the % operator. When you need to chain
   several expressions in modular arithmetic with different
   divisors, it may be best to just split up the expression into
   several and use temporary variables to avoid a mod inside a
   mod.
     __________________________________________________________

5.7. List of GEL Operators

   Everything in GEL is really just an expression. Expressions are
   stringed together with different operators. As we have seen,
   even the separator is simply a binary operator in GEL. Here is
   a list of the operators in GEL.

   a;b
          The separator, just evaluates both a and b, but returns
          only the result of b.

   a=b
          The assignment operator. This assigns b to a (a must be
          a valid lvalue) (note however that this operator may be
          translated to == if used in a place where boolean
          expression is expected)

   a:=b
          The assignment operator. Assigns b to a (a must be a
          valid lvalue). This is different from = because it never
          gets translated to a ==.

   |a|
          Absolute value. In case the expression is a complex
          number the result will be the modulus (distance from the
          origin). For example: |3 * e^(1i*pi)| returns 3.

          See Mathworld for more information.

   a^b
          Exponentiation, raises a to the bth power.

   a.^b
          Element by element exponentiation. Raise each element of
          a matrix a to the bth power. Or if b is a matrix of the
          same size as a, then do the operation element by
          element. If a is a number and b is a matrix then it
          creates matrix of the same size as b with a raised to
          all the different powers in b.

   a+b
          Addition. Adds two numbers, matrices, functions or
          strings. If you add a string to anything the result will
          just be a string. If one is a square matrix and the
          other a number, then the number is multiplied by the
          identity matrix.

   a-b
          Subtraction. Subtract two numbers, matrices or
          functions.

   a*b
          Multiplication. This is the normal matrix
          multiplication.

   a.*b
          Element by element multiplication if a and b are
          matrices.

   a/b
          Division. When a and b are just numbers this is the
          normal division. When they are matrices, then this is
          equivalent to a*b^-1.

   a./b
          Element by element division. Same as a/b for numbers,
          but operates element by element on matrices.

   a\b
          Back division. That is this is the same as b/a.

   a.\b
          Element by element back division.

   a%b
          The mod operator. This does not turn on the modular
          mode, but just returns the remainder of integer division
          a/b.

   a.%b
          Element by element mod operator. Returns the remainder
          after element by element integer division a./b.

   a mod b
          Modular evaluation operator. The expression a is
          evaluated modulo b. See Section 5.6. Some functions and
          operators behave differently modulo an integer.

   a!
          Factorial operator. This is like 1*...*(n-2)*(n-1)*n.

   a!!
          Double factorial operator. This is like
          1*...*(n-4)*(n-2)*n.

   a==b
          Equality operator. Returns true or false depending on a
          and b being equal or not.

   a!=b
          Inequality operator, returns true if a does not equal b
          else returns false.

   a<>b
          Alternative inequality operator, returns true if a does
          not equal b else returns false.

   a<=b
          Less than or equal operator, returns true if a is less
          than or equal to b else returns false. These can be
          chained as in a <= b <= c (can also be combined with the
          less than operator).

   a>=b
          Greater than or equal operator, returns true if a is
          greater than or equal to b else returns false. These can
          be chained as in a >= b >= c (and they can also be
          combined with the greater than operator).

   a<b
          Less than operator, returns true if a is less than b
          else returns false. These can be chained as in a < b < c
          (they can also be combined with the less than or equal
          to operator).

   a>b
          Greater than operator, returns true if a is greater than
          b else returns false. These can be chained as in a > b >
          c (they can also be combined with the greater than or
          equal to operator).

   a<=>b
          Comparison operator. If a is equal to b it returns 0, if
          a is less than b it returns -1 and if a is greater than
          b it returns 1.

   a and b
          Logical and. Returns true if both a and b are true, else
          returns false. If given numbers, nonzero numbers are
          treated as true.

   a or b
          Logical or. Returns true if either a or b is true, else
          returns false. If given numbers, nonzero numbers are
          treated as true.

   a xor b
          Logical xor. Returns true if exactly one of a or b is
          true, else returns false. If given numbers, nonzero
          numbers are treated as true.

   not a
          Logical not. Returns the logical negation of a.

   -a
          Negation operator. Returns the negative of a number or a
          matrix (works element-wise on a matrix).

   &a
          Variable referencing (to pass a reference to a
          variable). See Section 6.8.

   *a
          Variable dereferencing (to access a referenced
          variable). See Section 6.8.

   a'
          Matrix conjugate transpose. That is, rows and columns
          get swapped and we take complex conjugate of all
          entries. That is if the i,j element of a is x+iy, then
          the j,i element of a' is x-iy.

   a.'
          Matrix transpose, does not conjugate the entries. That
          is, the i,j element of a becomes the j,i element of a.'.

   a@(b,c)
          Get element of a matrix in row b and column c. If b, c
          are vectors, then this gets the corresponding rows,
          columns or submatrices.

   a@(b,)
          Get row of a matrix (or multiple rows if b is a vector).

   a@(b,:)
          Same as above.

   a@(,c)
          Get column of a matrix (or columns if c is a vector).

   a@(:,c)
          Same as above.

   a@(b)
          Get an element from a matrix treating it as a vector.
          This will traverse the matrix row-wise.

   a:b
          Build a vector from a to b (or specify a row, column
          region for the @ operator). For example to get rows 2 to
          4 of matrix A we could do

A@(2:4,)

          as 2:4 will return a vector [2,3,4].

   a:b:c
          Build a vector from a to c with b as a step. That is for
          example

genius> 1:2:9
=
`[1, 3, 5, 7, 9]

          When the numbers involved are floating point numbers,
          for example 1.0:0.4:3.0, the output is what is expected
          even though adding 0.4 to 1.0 five times is actually
          just slightly more than 3.0 due to the way that floating
          point numbers are stored in base 2 (there is no 0.4, the
          actual number stored is just ever so slightly bigger).
          The way this is handled is the same as in the for, sum,
          and prod loops. If the end is within 2^-20 times the
          step size of the endpoint, the endpoint is used and we
          assume there were roundoff errors. This is not perfect,
          but it handles the majority of the cases. This check is
          done only from version 1.0.18 onwards, so execution of
          your code may differ on older versions. If you want to
          avoid dealing with this issue, use actual rational
          numbers, possibly using the float if you wish to get
          floating point numbers in the end. For example 1:2/5:3
          does the right thing and float(1:2/5:3) even gives you
          floating point numbers and is ever so slightly more
          precise than 1.0:0.4:3.0.

   (a)i
          Make a into an imaginary number (multiply a by the
          imaginary). Normally the imaginary number i is written
          as 1i. So the above is equal to

(a)*1i

   `a
          Quote an identifier so that it doesn't get evaluated. Or
          quote a matrix so that it doesn't get expanded.

   a swapwith b
          Swap value of a with the value of b. Currently does not
          operate on ranges of matrix elements. It returns null.
          Available from version 1.0.13.

   increment a
          Increment the variable a by 1. If a is a matrix, then
          increment each element. This is equivalent to a=a+1, but
          it is somewhat faster. It returns null. Available from
          version 1.0.13.

   increment a by b
          Increment the variable a by b. If a is a matrix, then
          increment each element. This is equivalent to a=a+b, but
          it is somewhat faster. It returns null. Available from
          version 1.0.13.

   Note

   The @() operator makes the : operator most useful. With this
   you can specify regions of a matrix. So that a@(2:4,6) is the
   rows 2,3,4 of the column 6. Or a@(,1:2) will get you the first
   two columns of a matrix. You can also assign to the @()
   operator, as long as the right value is a matrix that matches
   the region in size, or if it is any other type of value.

   Note

   The comparison operators (except for the <=> operator, which
   behaves normally), are not strictly binary operators, they can
   in fact be grouped in the normal mathematical way, e.g.:
   (1<x<=y<5) is a legal boolean expression and means just what it
   should, that is (1<x and x≤y and y<5)

   Note

   The unitary minus operates in a different fashion depending on
   where it appears. If it appears before a number it binds very
   closely, if it appears in front of an expression it binds less
   than the power and factorial operators. So for example -1^k is
   really (-1)^k, but -foo(1)^k is really -(foo(1)^k). So be
   careful how you use it and if in doubt, add parentheses.
     __________________________________________________________

Chapter 6. Programming with GEL

6.1. Conditionals

   Syntax:
if <expression1> then <expression2> [else <expression3>]

   If else is omitted, then if the expression1 yields false or 0,
   NULL is returned.

   Examples:
if(a==5)then(a=a-1)
if b<a then b=a
if c>0 then c=c-1 else c=0
a = ( if b>0 then b else 1 )

   Note that = will be translated to == if used inside the
   expression for if, so
if a=5 then a=a-1

   will be interpreted as:
if a==5 then a:=a-1
     __________________________________________________________

6.2. Loops

6.2.1. While Loops

   Syntax:
while <expression1> do <expression2>
until <expression1> do <expression2>
do <expression2> while <expression1>
do <expression2> until <expression1>

   These are similar to other languages. However, as in GEL it is
   simply an expression that must have some return value, these
   constructs will simply return the result of the last iteration
   or NULL if no iteration was done. In the boolean expression, =
   is translated into == just as for the if statement.
     __________________________________________________________

6.2.2. For Loops

   Syntax:
for <identifier> = <from> to <to> do <body>
for <identifier> = <from> to <to> by <increment> do <body>

   Loop with identifier being set to all values from <from> to
   <to>, optionally using an increment other than 1. These are
   faster, nicer and more compact than the normal loops such as
   above, but less flexible. The identifier must be an identifier
   and can't be a dereference. The value of identifier is the last
   value of identifier, or <from> if body was never evaluated. The
   variable is guaranteed to be initialized after a loop, so you
   can safely use it. Also the <from>, <to> and <increment> must
   be non complex values. The <to> is not guaranteed to be hit,
   but will never be overshot, for example the following prints
   out odd numbers from 1 to 19:
for i = 1 to 20 by 2 do print(i)

   When one of the values is a floating point number, then the
   final check is done to within 2^-20 of the step size. That is,
   even if we overshoot by 2^-20 times the "by" above, we still
   execute the last iteration. This way
for x = 0 to 1 by 0.1 do print(x)

   does the expected even though adding 0.1 ten times becomes just
   slightly more than 1.0 due to the way that floating point
   numbers are stored in base 2 (there is no 0.1, the actual
   number stored is just ever so slightly bigger). This is not
   perfect but it handles the majority of the cases. If you want
   to avoid dealing with this issue, use actual rational numbers
   for example:
for x = 0 to 1 by 1/10 do print(x)

   This check is done only from version 1.0.16 onwards, so
   execution of your code may differ on older versions.
     __________________________________________________________

6.2.3. Foreach Loops

   Syntax:
for <identifier> in <matrix> do <body>

   For each element in the matrix, going row by row from left to
   right we execute the body with the identifier set to the
   current element. To print numbers 1,2,3 and 4 in this order you
   could do:
for n in [1,2:3,4] do print(n)

   If you wish to run through the rows and columns of a matrix,
   you can use the RowsOf and ColumnsOf functions, which return a
   vector of the rows or columns of the matrix. So,
for n in RowsOf ([1,2:3,4]) do print(n)

   will print out [1,2] and then [3,4].
     __________________________________________________________

6.2.4. Break and Continue

   You can also use the break and continue commands in loops. The
   continue continue command will restart the current loop at its
   next iteration, while the break command exits the current loop.
while(<expression1>) do (
  if(<expression2>) break
  else if(<expression3>) continue;
  <expression4>
)
     __________________________________________________________

6.3. Sums and Products

   Syntax:
sum <identifier> = <from> to <to> do <body>
sum <identifier> = <from> to <to> by <increment> do <body>
sum <identifier> in <matrix> do <body>
prod <identifier> = <from> to <to> do <body>
prod <identifier> = <from> to <to> by <increment> do <body>
prod <identifier> in <matrix> do <body>

   If you substitute for with sum or prod, then you will get a sum
   or a product instead of a for loop. Instead of returning the
   last value, these will return the sum or the product of the
   values respectively.

   If no body is executed (for example sum i=1 to 0 do ...) then
   sum returns 0 and prod returns 1 as is the standard convention.

   For floating point numbers the same roundoff error protection
   is done as in the for loop. See Section 6.2.2.
     __________________________________________________________

6.4. Comparison Operators

   The following standard comparison operators are supported in
   GEL and have the obvious meaning: ==, >=, <=, !=, <>, <, >.
   They return true or false. The operators != and <> are the same
   thing and mean "is not equal to". GEL also supports the
   operator <=>, which returns -1 if left side is smaller, 0 if
   both sides are equal, 1 if left side is larger.

   Normally = is translated to == if it happens to be somewhere
   where GEL is expecting a condition such as in the if condition.
   For example
if a=b then c
if a==b then c

   are the same thing in GEL. However you should really use == or
   := when you want to compare or assign respectively if you want
   your code to be easy to read and to avoid mistakes.

   All the comparison operators (except for the <=> operator,
   which behaves normally), are not strictly binary operators,
   they can in fact be grouped in the normal mathematical way,
   e.g.: (1<x<=y<5) is a legal boolean expression and means just
   what it should, that is (1<x and x≤y and y<5)

   To build up logical expressions use the words not, and, or,
   xor. The operators or and and are special beasts as they
   evaluate their arguments one by one, so the usual trick for
   conditional evaluation works here as well. For example, 1 or
   a=1 will not set a=1 since the first argument was true.
     __________________________________________________________

6.5. Global Variables and Scope of Variables

   GEL is a dynamically scoped language. We will explain what this
   means below. That is, normal variables and functions are
   dynamically scoped. The exception are parameter variables,
   which are always global.

   Like most programming languages, GEL has different types of
   variables. Normally when a variable is defined in a function,
   it is visible from that function and from all functions that
   are called (all higher contexts). For example, suppose a
   function f defines a variable a and then calls function g. Then
   function g can reference a. But once f returns, the variable a
   goes out of scope. For example, the following code will print
   out 5. The function g cannot be called on the top level
   (outside f as a will not be defined).
function f() = (a:=5; g());
function g() = print(a);
f();

   If you define a variable inside a function it will override any
   variables defined in calling functions. For example, we modify
   the above code and write:
function f() = (a:=5; g());
function g() = print(a);
a:=10;
f();

   This code will still print out 5. But if you call g outside of
   f then you will get a printout of 10. Note that setting a to 5
   inside f does not change the value of a at the top (global)
   level, so if you now check the value of a it will still be 10.

   Function arguments are exactly like variables defined inside
   the function, except that they are initialized with the value
   that was passed to the function. Other than this point, they
   are treated just like all other variables defined inside the
   function.

   Functions are treated exactly like variables. Hence you can
   locally redefine functions. Normally (on the top level) you
   cannot redefine protected variables and functions. But locally
   you can do this. Consider the following session:
genius> function f(x) = sin(x)^2
= (`(x)=(sin(x)^2))
genius> function f(x) = sin(x)^2
= (`(x)=(sin(x)^2))
genius> function g(x) = ((function sin(x)=x^10);f(x))
= (`(x)=((sin:=(`(x)=(x^10)));f(x)))
genius> g(10)
= 1e20

   Functions and variables defined at the top level are considered
   global. They are visible from anywhere. As we said the
   following function f will not change the value of a to 5.
a=6;
function f() = (a:=5);
f();

   Sometimes, however, it is necessary to set a global variable
   from inside a function. When this behavior is needed, use the
   set function. Passing a string or a quoted identifier to this
   function sets the variable globally (on the top level). For
   example, to set a to the value 3 you could call:
set(`a,3)

   or:
set("a",3)

   The set function always sets the toplevel global. There is no
   way to set a local variable in some function from a subroutine.
   If this is required, must use passing by reference.

   See also the SetElement and SetVElement functions.

   So to recap in a more technical language: Genius operates with
   different numbered contexts. The top level is the context 0
   (zero). Whenever a function is entered, the context is raised,
   and when the function returns the context is lowered. A
   function or a variable is always visible from all higher
   numbered contexts. When a variable was defined in a lower
   numbered context, then setting this variable has the effect of
   creating a new local variable in the current context number and
   this variable will now be visible from all higher numbered
   contexts.

   There are also true local variables that are not seen from
   anywhere but the current context. Also when returning functions
   by value it may reference variables not visible from higher
   context and this may be a problem. See the sections True Local
   Variables and Returning Functions.
     __________________________________________________________

6.6. Parameter variables

   As we said before, there exist special variables called
   parameters that exist in all scopes. To declare a parameter
   called foo with the initial value 1, we write
parameter foo = 1

   From then on, foo is a strictly global variable. Setting foo
   inside any function will modify the variable in all contexts,
   that is, functions do not have a private copy of parameters.

   When you undefine a parameter using the undefine function, it
   stops being a parameter.

   Some parameters are built-in and modify the behavior of genius.
     __________________________________________________________

6.7. Returning

   Normally a function is one or several expressions separated by
   a semicolon, and the value of the last expression is returned.
   This is fine for simple functions, but sometimes you do not
   want a function to return the last thing calculated. You may,
   for example, want to return from a middle of a function. In
   this case, you can use the return keyword. return takes one
   argument, which is the value to be returned.

   Example:
function f(x) = (
  y=1;
  while true do (
    if x>50 then return y;
    y=y+1;
    x=x+1
  )
)
     __________________________________________________________

6.8. References

   It may be necessary for some functions to return more than one
   value. This may be accomplished by returning a vector of
   values, but many times it is convenient to use passing a
   reference to a variable. You pass a reference to a variable to
   a function, and the function will set the variable for you
   using a dereference. You do not have to use references only for
   this purpose, but this is their main use.

   When using functions that return values through references in
   the argument list, just pass the variable name with an
   ampersand. For example the following code will compute an
   eigenvalue of a matrix A with initial eigenvector guess x, and
   store the computed eigenvector into the variable named v:
RayleighQuotientIteration (A,x,0.001,100,&v)

   The details of how references work and the syntax is similar to
   the C language. The operator & references a variable and *
   dereferences a variable. Both can only be applied to an
   identifier, so **a is not a legal expression in GEL.

   References are best explained by an example:
a=1;
b=&a;
*b=2;

   now a contains 2. You can also reference functions:
function f(x) = x+1;
t=&f;
*t(3)

   gives us 4.
     __________________________________________________________

6.9. Lvalues

   An lvalue is the left hand side of an assignment. In other
   words, an lvalue is what you assign something to. Valid lvalues
   are:

   a
          Identifier. Here we would be setting the variable of
          name a.

   *a
          Dereference of an identifier. This will set whatever
          variable a points to.

   a@(<region>)
          A region of a matrix. Here the region is specified
          normally as with the regular @() operator, and can be a
          single entry, or an entire region of the matrix.

   Examples:
a:=4
*tmp := 89
a@(1,1) := 5
a@(4:8,3) := [1,2,3,4,5]'

   Note that both := and = can be used interchangeably. Except if
   the assignment appears in a condition. It is thus always safer
   to just use := when you mean assignment, and == when you mean
   comparison.
     __________________________________________________________

Chapter 7. Advanced Programming with GEL

7.1. Error Handling

   If you detect an error in your function, you can bail out of
   it. For normal errors, such as wrong types of arguments, you
   can fail to compute the function by adding the statement
   bailout. If something went really wrong and you want to
   completely kill the current computation, you can use exception.

   For example if you want to check for arguments in your
   function. You could use the following code.
function f(M) = (
  if not IsMatrix (M) then (
    error ("M not a matrix!");
    bailout
  );
  ...
)
     __________________________________________________________

7.2. Toplevel Syntax

   The syntax is slightly different if you enter statements on the
   top level versus when they are inside parentheses or inside
   functions. On the top level, enter acts the same as if you
   press return on the command line. Therefore think of programs
   as just a sequence of lines as if they were entered on the
   command line. In particular, you do not need to enter the
   separator at the end of the line (unless it is of course part
   of several statements inside parentheses). When a statement
   does not end with a separator on the top level, the result is
   printed after being executed.

   For example,
function f(x)=x^2
f(3)

   will print first the result of setting a function (a
   representation of the function, in this case (`(x)=(x^2))) and
   then the expected 9. To avoid this, enter a separator after the
   function definition.
function f(x)=x^2;
f(3)

   If you need to put a separator into your function then you have
   to surround with parenthesis. For example:
function f(x)=(
  y=1;
  for j=1 to x do
    y = y+j;
  y^2
);

   The following code will produce an error when entered on the
   top level of a program, while it will work just fine in a
   function.
if Something() then
  DoSomething()
else
  DoSomethingElse()

   The problem is that after Genius Mathematics Tool sees the end
   of line after the second line, it will decide that we have
   whole statement and it will execute it. After the execution is
   done, Genius Mathematics Tool will go on to the next line, it
   will see else, and it will produce a parsing error. To fix
   this, use parentheses. Genius Mathematics Tool will not be
   satisfied until it has found that all parentheses are closed.
if Something() then (
  DoSomething()
) else (
  DoSomethingElse()
)
     __________________________________________________________

7.3. Returning Functions

   It is possible to return functions as value. This way you can
   build functions that construct special purpose functions
   according to some parameters. The tricky bit is what variables
   does the function see. The way this works in GEL is that when a
   function returns another function, all identifiers referenced
   in the function body that went out of scope are prepended a
   private dictionary of the returned function. So the function
   will see all variables that were in scope when it was defined.
   For example, we define a function that returns a function that
   adds 5 to its argument.
function f() = (
  k = 5;
  `(x) = (x+k)
)

   Notice that the function adds k to x. You could use this as
   follows.
g = f();
g(5)

   And g(5) should return 10.

   One thing to note is that the value of k that is used is the
   one that's in effect when the f returns. For example:
function f() = (
  k := 5;
  function r(x) = (x+k);
  k := 10;
  r
)

   will return a function that adds 10 to its argument rather than
   5. This is because the extra dictionary is created only when
   the context in which the function was defined ends, which is
   when the function f returns. This is consistent with how you
   would expect the function r to work inside the function f
   according to the rules of scope of variables in GEL. Only those
   variables are added to the extra dictionary that are in the
   context that just ended and no longer exists. Variables used in
   the function that are in still valid contexts will work as
   usual, using the current value of the variable. The only
   difference is with global variables and functions. All
   identifiers that referenced global variables at time of the
   function definition are not added to the private dictionary.
   This is to avoid much unnecessary work when returning functions
   and would rarely be a problem. For example, suppose that you
   delete the "k=5" from the function f, and at the top level you
   define k to be say 5. Then when you run f, the function r will
   not put k into the private dictionary because it was global
   (toplevel) at the time of definition of r.

   Sometimes it is better to have more control over how variables
   are copied into the private dictionary. Since version 1.0.7,
   you can specify which variables are copied into the private
   dictionary by putting extra square brackets after the arguments
   with the list of variables to be copied separated by commas. If
   you do this, then variables are copied into the private
   dictionary at time of the function definition, and the private
   dictionary is not touched afterwards. For example
function f() = (
  k := 5;
  function r(x) [k] = (x+k);
  k := 10;
  r
)

   will return a function that when called will add 5 to its
   argument. The local copy of k was created when the function was
   defined.

   When you want the function to not have any private dictionary
   then put empty square brackets after the argument list. Then no
   private dictionary will be created at all. Doing this is good
   to increase efficiency when a private dictionary is not needed
   or when you want the function to lookup all variables as it
   sees them when called. For example suppose you want the
   function returned from f to see the value of k from the
   toplevel despite there being a local variable of the same name
   during definition. So the code
function f() = (
  k := 5;
  function r(x) [] = (x+k);
  r
);
k := 10;
g = f();
g(10)

   will return 20 and not 15, which would happen if k with a value
   of 5 was added to the private dictionary.
     __________________________________________________________

7.4. True Local Variables

   When passing functions into other functions, the normal scoping
   of variables might be undesired. For example:
k := 10;
function r(x) = (x+k);
function f(g,x) = (
  k := 5;
  g(x)
);
f(r,1)

   you probably want the function r when passed as g into f to see
   k as 10 rather than 5, so that the code returns 11 and not 6.
   However, as written, the function when executed will see the k
   that is equal to 5. There are two ways to solve this. One would
   be to have r get k in a private dictionary using the square
   bracket notation section Returning Functions.

   But there is another solution. Since version 1.0.7 there are
   true local variables. These are variables that are visible only
   from the current context and not from any called functions. We
   could define k as a local variable in the function f. To do
   this add a local statement as the first statement in the
   function (it must always be the first statement in the
   function). You can also make any arguments be local variables
   as well. That is,
function f(g,x) = (
  local g,x,k;
  k := 5;
  g(x)
);

   Then the code will work as expected and prints out 11. Note
   that the local statement initializes all the referenced
   variables (except for function arguments) to a null.

   If all variables are to be created as locals you can just pass
   an asterisk instead of a list of variables. In this case the
   variables will not be initialized until they are actually set
   of course. So the following definition of f will also work:
function f(g,x) = (
  local *;
  k := 5;
  g(x)
);

   It is good practice that all functions that take other
   functions as arguments use local variables. This way the passed
   function does not see implementation details and get confused.
     __________________________________________________________

7.5. GEL Startup Procedure

   First the program looks for the installed library file (the
   compiled version lib.cgel) in the installed directory, then it
   looks into the current directory, and then it tries to load an
   uncompiled file called ~/.geniusinit.

   If you ever change the library in its installed place, you’ll
   have to first compile it with genius --compile loader.gel >
   lib.cgel
     __________________________________________________________

7.6. Loading Programs

   Sometimes you have a larger program you wrote into a file and
   want to read that file into Genius Mathematics Tool. In these
   situations, you have two options. You can keep the functions
   you use most inside the ~/.geniusinit file. Or if you want to
   load up a file in a middle of a session (or from within another
   file), you can type load <list of filenames> at the prompt.
   This has to be done on the top level and not inside any
   function or whatnot, and it cannot be part of any expression.
   It also has a slightly different syntax than the rest of
   genius, more similar to a shell. You can enter the file in
   quotes. If you use the '' quotes, you will get exactly the
   string that you typed, if you use the "" quotes, special
   characters will be unescaped as they are for strings. Example:
load program1.gel program2.gel
load "Weird File Name With SPACES.gel"

   There are also cd, pwd and ls commands built in. cd will take
   one argument, ls will take an argument that is like the glob in
   the UNIX shell (i.e., you can use wildcards). pwd takes no
   arguments. For example:
cd directory_with_gel_programs
ls *.gel
     __________________________________________________________

Chapter 8. Matrices in GEL

   Genius has support for vectors and matrices and possesses a
   sizable library of matrix manipulation and linear algebra
   functions.
     __________________________________________________________

8.1. Entering Matrices

   To enter matrices, you can use one of the following two
   syntaxes. You can either enter the matrix on one line,
   separating values by commas and rows by semicolons. Or you can
   enter each row on one line, separating values by commas. You
   can also just combine the two methods. So to enter a 3x3 matrix
   of numbers 1-9 you could do
[1,2,3;4,5,6;7,8,9]

   or
[1, 2, 3
 4, 5, 6
 7, 8, 9]

   Do not use both ';' and return at once on the same line though.

   You can also use the matrix expansion functionality to enter
   matrices. For example you can do:
a = [ 1, 2, 3
      4, 5, 6
      7, 8, 9]
b = [ a,  10
      11, 12]

   and you should get
[1,   2,  3, 10
 4,   5,  6, 10
 7,   8,  9, 10
 11, 11, 11, 12]

   similarly you can build matrices out of vectors and other stuff
   like that.

   Another thing is that non-specified spots are initialized to 0,
   so
[1, 2, 3
 4, 5
 6]

   will end up being
[1, 2, 3
 4, 5, 0
 6, 0, 0]

   When matrices are evaluated, they are evaluated and traversed
   row-wise. This is just like the M@(j) operator, which traverses
   the matrix row-wise.

   Note

   Be careful about using returns for expressions inside the [ ]
   brackets, as they have a slightly different meaning there. You
   will start a new row.
     __________________________________________________________

8.2. Conjugate Transpose and Transpose Operator

   You can conjugate transpose a matrix by using the ' operator.
   That is the entry in the ith column and the jth row will be the
   complex conjugate of the entry in the jth column and the ith
   row of the original matrix. For example:
[1,2,3]*[4,5,6]'

   We transpose the second vector to make matrix multiplication
   possible. If you just want to transpose a matrix without
   conjugating it, you would use the .' operator. For example:
[1,2,3]*[4,5,6i].'

   Note that normal transpose, that is the .' operator, is much
   faster and will not create a new copy of the matrix in memory.
   The conjugate transpose does create a new copy unfortunately.
   It is recommended to always use the .' operator when working
   with real matrices and vectors.
     __________________________________________________________

8.3. Linear Algebra

   Genius implements many useful linear algebra and matrix
   manipulation routines. See the Linear Algebra and Matrix
   Manipulation sections of the GEL function listing.

   The linear algebra routines implemented in GEL do not currently
   come from a well tested numerical package, and thus should not
   be used for critical numerical computation. On the other hand,
   Genius implements very well many linear algebra operations with
   rational and integer coefficients. These are inherently exact
   and in fact will give you much better results than common
   double precision routines for linear algebra.

   For example, it is pointless to compute the rank and nullspace
   of a floating point matrix since for all practical purposes, we
   need to consider the matrix as having some slight errors. You
   are likely to get a different result than you expect. The
   problem is that under a small perturbation every matrix is of
   full rank and invertible. If the matrix however is of rational
   numbers, then the rank and nullspace are always exact.

   In general when Genius computes the basis of a certain
   vectorspace (for example with the NullSpace) it will give the
   basis as a matrix, in which the columns are the vectors of the
   basis. That is, when Genius talks of a linear subspace it means
   a matrix whose column space is the given linear subspace.

   It should be noted that Genius can remember certain properties
   of a matrix. For example, it will remember that a matrix is in
   row reduced form. If many calls are made to functions that
   internally use row reduced form of the matrix, we can just row
   reduce the matrix beforehand once. Successive calls to rref
   will be very fast.
     __________________________________________________________

Chapter 9. Polynomials in GEL

   Currently Genius can handle polynomials of one variable written
   out as vectors, and do some basic operations with these. It is
   planned to expand this support further.
     __________________________________________________________

9.1. Using Polynomials

   Currently polynomials in one variable are just horizontal
   vectors with value only nodes. The power of the term is the
   position in the vector, with the first position being 0. So,
[1,2,3]

   translates to a polynomial of
1 + 2*x + 3*x^2

   You can add, subtract and multiply polynomials using the
   AddPoly, SubtractPoly, and MultiplyPoly functions respectively.
   You can print a polynomial using the PolyToString function. For
   example,
PolyToString([1,2,3],"y")

   gives
3*y^2 + 2*y + 1

   You can also get a function representation of the polynomial so
   that you can evaluate it. This is done by using PolyToFunction,
   which returns an anonymous function.
f = PolyToFunction([0,1,1])
f(2)

   It is also possible to find roots of polynomials of degrees 1
   through 4 by using the function PolynomialRoots, which calls
   the appropriate formula function. Higher degree polynomials
   must be converted to functions and solved numerically using a
   function such as FindRootBisection, FindRootFalsePosition,
   FindRootMullersMethod, or FindRootSecant.

   See Section 11.15 in the function list for the rest of
   functions acting on polynomials.
     __________________________________________________________

Chapter 10. Set Theory in GEL

   Genius has some basic set theoretic functionality built in.
   Currently a set is just a vector (or a matrix). Every distinct
   object is treated as a different element.
     __________________________________________________________

10.1. Using Sets

   Just like vectors, objects in sets can include numbers,
   strings, null, matrices and vectors. It is planned in the
   future to have a dedicated type for sets, rather than using
   vectors. Note that floating point numbers are distinct from
   integers, even if they appear the same. That is, Genius will
   treat 0 and 0.0 as two distinct elements. The null is treated
   as an empty set.

   To build a set out of a vector, use the MakeSet function.
   Currently, it will just return a new vector where every element
   is unique.
genius> MakeSet([1,2,2,3])
= [1, 2, 3]

   Similarly there are functions Union, Intersection, SetMinus,
   which are rather self explanatory. For example:
genius> Union([1,2,3], [1,2,4])
= [1, 2, 4, 3]

   Note that no order is guaranteed for the return values. If you
   wish to sort the vector you should use the SortVector function.

   For testing membership, there are functions IsIn and IsSubset,
   which return a boolean value. For example:
genius> IsIn (1, [0,1,2])
= true

   The input IsIn(x,X) is of course equivalent to IsSubset([x],X).
   Note that since the empty set is a subset of every set,
   IsSubset(null,X) is always true.
     __________________________________________________________

Chapter 11. List of GEL functions

   To get help on a specific function from the console type:
help FunctionName
     __________________________________________________________

11.1. Commands

   help

help

help FunctionName

          Print help (or help on a function/command).

   load

load "file.gel"

          Load a file into the interpreter. The file will execute
          as if it were typed onto the command line.

   cd

cd /directory/name

          Change working directory to /directory/name.

   pwd

pwd

          Print the current working directory.

   ls

ls

          List files in the current directory.

   plugin

plugin plugin_name

          Load a plugin. Plugin of that name must be installed on
          the system in the proper directory.
     __________________________________________________________

11.2. Basic

   AskButtons

AskButtons (query)

AskButtons (query, button1, ...)

          Asks a question and presents a list of buttons to the
          user (or a menu of options in text mode). Returns the
          1-based index of the button pressed. That is, returns 1
          if the first button was pressed, 2 if the second button
          was pressed, and so on. If the user closes the window
          (or simply hits enter in text mode), then null is
          returned. The execution of the program is blocked until
          the user responds.

          Version 1.0.10 onwards.

   AskString

AskString (query)

AskString (query, default)

          Asks a question and lets the user enter a string, which
          it then returns. If the user cancels or closes the
          window, then null is returned. The execution of the
          program is blocked until the user responds. If default
          is given, then it is pre-typed in for the user to just
          press enter on (version 1.0.6 onwards).

   Compose

Compose (f,g)

          Compose two functions and return a function that is the
          composition of f and g.

   ComposePower

ComposePower (f,n,x)

          Compose and execute a function with itself n times,
          passing x as argument. Returning x if n equals 0.
          Example:

genius> function f(x) = x^2 ;
genius> ComposePower (f,3,7)
= 5764801
genius> f(f(f(7)))
= 5764801

   Evaluate

Evaluate (str)

          Parses and evaluates a string.

   GetCurrentModulo

GetCurrentModulo

          Get current modulo from the context outside the
          function. That is, if outside of the function was
          executed in modulo (using mod) then this returns what
          this modulo was. Normally the body of the function
          called is not executed in modular arithmetic, and this
          builtin function makes it possible to make GEL functions
          aware of modular arithmetic.

   Identity

Identity (x)

          Identity function, returns its argument. It is
          equivalent to function Identity(x)=x.

   IntegerFromBoolean

IntegerFromBoolean (bval)

          Make integer (0 for false or 1 for true) from a boolean
          value. bval can also be a number in which case a
          non-zero value will be interpreted as true and zero will
          be interpreted as false.

   IsBoolean

IsBoolean (arg)

          Check if argument is a boolean (and not a number).

   IsDefined

IsDefined (id)

          Check if an id is defined. You should pass a string or
          and identifier. If you pass a matrix, each entry will be
          evaluated separately and the matrix should contain
          strings or identifiers.

   IsFunction

IsFunction (arg)

          Check if argument is a function.

   IsFunctionOrIdentifier

IsFunctionOrIdentifier (arg)

          Check if argument is a function or an identifier.

   IsFunctionRef

IsFunctionRef (arg)

          Check if argument is a function reference. This includes
          variable references.

   IsMatrix

IsMatrix (arg)

          Check if argument is a matrix. Even though null is
          sometimes considered an empty matrix, the function
          IsMatrix does not consider null a matrix.

   IsNull

IsNull (arg)

          Check if argument is a null.

   IsString

IsString (arg)

          Check if argument is a text string.

   IsValue

IsValue (arg)

          Check if argument is a number.

   Parse

Parse (str)

          Parses but does not evaluate a string. Note that certain
          pre-computation is done during the parsing stage.

   SetFunctionFlags

SetFunctionFlags (id,flags...)

          Set flags for a function, currently "PropagateMod" and
          "NoModuloArguments". If "PropagateMod" is set, then the
          body of the function is evaluated in modular arithmetic
          when the function is called inside a block that was
          evaluated using modular arithmetic (using mod). If
          "NoModuloArguments", then the arguments of the function
          are never evaluated using modular arithmetic.

   SetHelp

SetHelp (id,category,desc)

          Set the category and help description line for a
          function.

   SetHelpAlias

SetHelpAlias (id,alias)

          Sets up a help alias.

   chdir

chdir (dir)

          Changes current directory, same as the cd.

   CurrentTime

CurrentTime

          Returns the current UNIX time with microsecond precision
          as a floating point number. That is, returns the number
          of seconds since January 1st 1970.

          Version 1.0.15 onwards.

   display

display (str,expr)

          Display a string and an expression with a colon to
          separate them.

   DisplayVariables

DisplayVariables (var1,var2,...)

          Display set of variables. The variables can be given as
          strings or identifiers. For example:

DisplayVariables(`x,`y,`z)

          If called without arguments (must supply empty argument
          list) as

DisplayVariables()

          then all variables are printed including a stacktrace
          similar to Show user variables in the graphical version.

          Version 1.0.18 onwards.

   error

error (str)

          Prints a string to the error stream (onto the console).

   exit

exit

          Aliases: quit

          Exits the program.

   false

false

          Aliases: False FALSE

          The false boolean value.

   manual

manual

          Displays the user manual.

   print

print (str)

          Prints an expression and then print a newline. The
          argument str can be any expression. It is made into a
          string before being printed.

   printn

printn (str)

          Prints an expression without a trailing newline. The
          argument str can be any expression. It is made into a
          string before being printed.

   PrintTable

PrintTable (f,v)

          Print a table of values for a function. The values are
          in the vector v. You can use the vector building
          notation as follows:

PrintTable (f,[0:10])

          If v is a positive integer, then the table of integers
          from 1 up to and including v will be used.

          Version 1.0.18 onwards.

   protect

protect (id)

          Protect a variable from being modified. This is used on
          the internal GEL functions to avoid them being
          accidentally overridden.

   ProtectAll

ProtectAll ()

          Protect all currently defined variables, parameters and
          functions from being modified. This is used on the
          internal GEL functions to avoid them being accidentally
          overridden. Normally Genius Mathematics Tool considers
          unprotected variables as user defined.

          Version 1.0.7 onwards.

   set

set (id,val)

          Set a global variable. The id can be either a string or
          a quoted identifier. For example:

set(`x,1)

          will set the global variable x to the value 1.

          The function returns the val, to be usable in chaining.

   SetElement

SetElement (id,row,col,val)

          Set an element of a global variable which is a matrix.
          The id can be either a string or a quoted identifier.
          For example:

SetElement(`x,2,3,1)

          will set the second row third column element of the
          global variable x to the value 1. If no global variable
          of the name exists, or if it is set to something that's
          not a matrix, a new zero matrix of appropriate size will
          be created.

          The row and col can also be ranges, and the semantics
          are the same as for regular setting of the elements with
          an equals sign.

          The function returns the val, to be usable in chaining.

          Available from 1.0.18 onwards.

   SetVElement

SetElement (id,elt,val)

          Set an element of a global variable which is a vector.
          The id can be either a string or a quoted identifier.
          For example:

SetElement(`x,2,1)

          will set the second element of the global vector
          variable x to the value 1. If no global variable of the
          name exists, or if it is set to something that's not a
          vector (matrix), a new zero row vector of appropriate
          size will be created.

          The elt can also be a range, and the semantics are the
          same as for regular setting of the elements with an
          equals sign.

          The function returns the val, to be usable in chaining.

          Available from 1.0.18 onwards.

   string

string (s)

          Make a string. This will make a string out of any
          argument.

   true

true

          Aliases: True TRUE

          The true boolean value.

   undefine

undefine (id)

          Alias: Undefine

          Undefine a variable. This includes locals and globals,
          every value on all context levels is wiped. This
          function should really not be used on local variables. A
          vector of identifiers can also be passed to undefine
          several variables.

   UndefineAll

UndefineAll ()

          Undefine all unprotected global variables (including
          functions and parameters). Normally Genius Mathematics
          Tool considers protected variables as system defined
          functions and variables. Note that UndefineAll only
          removes the global definition of symbols not local ones,
          so that it may be run from inside other functions
          safely.

          Version 1.0.7 onwards.

   unprotect

unprotect (id)

          Unprotect a variable from being modified.

   UserVariables

UserVariables ()

          Return a vector of identifiers of user defined
          (unprotected) global variables.

          Version 1.0.7 onwards.

   wait

wait (secs)

          Waits a specified number of seconds. secs must be
          non-negative. Zero is accepted and nothing happens in
          this case, except possibly user interface events are
          processed.

          Since version 1.0.18, secs can be a noninteger number,
          so wait(0.1) will wait for one tenth of a second.

   version

version

          Returns the version of Genius as a horizontal 3-vector
          with major version first, then minor version and finally
          the patch level.

   warranty

warranty

          Gives the warranty information.
     __________________________________________________________

11.3. Parameters

   ChopTolerance

ChopTolerance = number

          Tolerance of the Chop function.

   ContinuousNumberOfTries

ContinuousNumberOfTries = number

          How many iterations to try to find the limit for
          continuity and limits.

   ContinuousSFS

ContinuousSFS = number

          How many successive steps to be within tolerance for
          calculation of continuity.

   ContinuousTolerance

ContinuousTolerance = number

          Tolerance for continuity of functions and for
          calculating the limit.

   DerivativeNumberOfTries

DerivativeNumberOfTries = number

          How many iterations to try to find the limit for
          derivative.

   DerivativeSFS

DerivativeSFS = number

          How many successive steps to be within tolerance for
          calculation of derivative.

   DerivativeTolerance

DerivativeTolerance = number

          Tolerance for calculating the derivatives of functions.

   ErrorFunctionTolerance

ErrorFunctionTolerance = number

          Tolerance of the ErrorFunction.

   FloatPrecision

FloatPrecision = number

          Floating point precision.

   FullExpressions

FullExpressions = boolean

          Print full expressions, even if more than a line.

   GaussDistributionTolerance

GaussDistributionTolerance = number

          Tolerance of the GaussDistribution function.

   IntegerOutputBase

IntegerOutputBase = number

          Integer output base.

   IsPrimeMillerRabinReps

IsPrimeMillerRabinReps = number

          Number of extra Miller-Rabin tests to run on a number
          before declaring it a prime in IsPrime.

   LinePlotDrawLegends

LinePlotDrawLegends = true

          Tells genius to draw the legends for line plotting
          functions such as LinePlot.

   LinePlotDrawAxisLabels

LinePlotDrawAxisLabels = true

          Tells genius to draw the axis labels for line plotting
          functions such as LinePlot.

          Version 1.0.16 onwards.

   LinePlotVariableNames

LinePlotVariableNames = ["x","y","z","t"]

          Tells genius which variable names are used as default
          names for line plotting functions such as LinePlot and
          friends.

          Version 1.0.10 onwards.

   LinePlotWindow

LinePlotWindow = [x1,x2,y1,y2]

          Sets the limits for line plotting functions such as
          LinePlot.

   MaxDigits

MaxDigits = number

          Maximum digits to display.

   MaxErrors

MaxErrors = number

          Maximum errors to display.

   MixedFractions

MixedFractions = boolean

          If true, mixed fractions are printed.

   NumericalIntegralFunction

NumericalIntegralFunction = function

          The function used for numerical integration in
          NumericalIntegral.

   NumericalIntegralSteps

NumericalIntegralSteps = number

          Steps to perform in NumericalIntegral.

   OutputChopExponent

OutputChopExponent = number

          When another number in the object being printed (a
          matrix or a value) is greater than
          10^-OutputChopWhenExponent, and the number being printed
          is less than 10^-OutputChopExponent, then display 0.0
          instead of the number.

          Output is never chopped if OutputChopExponent is zero.
          It must be a non-negative integer.

          If you want output always chopped according to
          OutputChopExponent, then set OutputChopWhenExponent, to
          something greater than or equal to OutputChopExponent.

   OutputChopWhenExponent

OutputChopWhenExponent = number

          When to chop output. See OutputChopExponent.

   OutputStyle

OutputStyle = string

          Output style, this can be normal, latex, mathml or
          troff.

          This affects mostly how matrices and fractions are
          printed out and is useful for pasting into documents.
          For example you can set this to the latex by:

OutputStyle = "latex"

   ResultsAsFloats

ResultsAsFloats = boolean

          Convert all results to floats before printing.

   ScientificNotation

ScientificNotation = boolean

          Use scientific notation.

   SlopefieldTicks

SlopefieldTicks = [vertical,horizontal]

          Sets the number of vertical and horizontal ticks in a
          slopefield plot. (See SlopefieldPlot).

          Version 1.0.10 onwards.

   SumProductNumberOfTries

SumProductNumberOfTries = number

          How many iterations to try for InfiniteSum and
          InfiniteProduct.

   SumProductSFS

SumProductSFS = number

          How many successive steps to be within tolerance for
          InfiniteSum and InfiniteProduct.

   SumProductTolerance

SumProductTolerance = number

          Tolerance for InfiniteSum and InfiniteProduct.

   SurfacePlotDrawLegends

SurfacePlotDrawLegends = true

          Tells genius to draw the legends for surface plotting
          functions such as SurfacePlot.

          Version 1.0.16 onwards.

   SurfacePlotVariableNames

SurfacePlotVariableNames = ["x","y","z"]

          Tells genius which variable names are used as default
          names for surface plotting functions using SurfacePlot.
          Note that the z does not refer to the dependent
          (vertical) axis, but to the independent complex variable
          z=x+iy.

          Version 1.0.10 onwards.

   SurfacePlotWindow

SurfacePlotWindow = [x1,x2,y1,y2,z1,z2]

          Sets the limits for surface plotting (See SurfacePlot).

   VectorfieldNormalized

VectorfieldNormalized = true

          Should the vectorfield plotting have normalized arrow
          length. If true, vector fields will only show direction
          and not magnitude. (See VectorfieldPlot).

   VectorfieldTicks

VectorfieldTicks = [vertical,horizontal]

          Sets the number of vertical and horizontal ticks in a
          vectorfield plot. (See VectorfieldPlot).

          Version 1.0.10 onwards.
     __________________________________________________________

11.4. Constants

   CatalanConstant

CatalanConstant

          Catalan's Constant, approximately 0.915... It is defined
          to be the series where terms are (-1^k)/((2*k+1)^2),
          where k ranges from 0 to infinity.

          See Wikipedia or Mathworld for more information.

   EulerConstant

EulerConstant

          Aliases: gamma

          Euler's constant gamma. Sometimes called the
          Euler-Mascheroni constant.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   GoldenRatio

GoldenRatio

          The Golden Ratio.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   Gravity

Gravity

          Free fall acceleration at sea level in meters per second
          squared. This is the standard gravity constant 9.80665.
          The gravity in your particular neck of the woods might
          be different due to different altitude and the fact that
          the earth is not perfectly round and uniform.

          See Wikipedia for more information.

   e

e

          The base of the natural logarithm. e^x is the
          exponential function exp. It is approximately
          2.71828182846... This number is sometimes called Euler's
          number, although there are several numbers that are also
          called Euler's. An example is the gamma constant:
          EulerConstant.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   pi

pi

          The number pi, that is the ratio of a circle's
          circumference to its diameter. This is approximately
          3.14159265359...

          See Wikipedia or Planetmath or Mathworld for more
          information.
     __________________________________________________________

11.5. Numeric

   AbsoluteValue

AbsoluteValue (x)

          Aliases: abs

          Absolute value of a number and if x is a complex value
          the modulus of x. I.e. this the distance of x to the
          origin. This is equivalent to |x|.

          See Wikipedia, Planetmath (absolute value), Planetmath
          (modulus), Mathworld (absolute value) or Mathworld
          (complex modulus) for more information.

   Chop

Chop (x)

          Replace very small number with zero.

   ComplexConjugate

ComplexConjugate (z)

          Aliases: conj Conj

          Calculates the complex conjugate of the complex number
          z. If z is a vector or matrix, all its elements are
          conjugated.

          See Wikipedia for more information.

   Denominator

Denominator (x)

          Get the denominator of a rational number.

          See Wikipedia for more information.

   FractionalPart

FractionalPart (x)

          Return the fractional part of a number.

          See Wikipedia for more information.

   Im

Im (z)

          Aliases: ImaginaryPart

          Get the imaginary part of a complex number. For example
          Re(3+4i) yields 4.

          See Wikipedia for more information.

   IntegerQuotient

IntegerQuotient (m,n)

          Division without remainder.

   IsComplex

IsComplex (num)

          Check if argument is a complex (non-real) number. Do
          note that we really mean nonreal number. That is,
          IsComplex(3) yields false, while IsComplex(3-1i) yields
          true.

   IsComplexRational

IsComplexRational (num)

          Check if argument is a possibly complex rational number.
          That is, if both real and imaginary parts are given as
          rational numbers. Of course rational simply means "not
          stored as a floating point number."

   IsFloat

IsFloat (num)

          Check if argument is a real floating point number
          (non-complex).

   IsGaussInteger

IsGaussInteger (num)

          Aliases: IsComplexInteger

          Check if argument is a possibly complex integer. That is
          a complex integer is a number of the form n+1i*m where n
          and m are integers.

   IsInteger

IsInteger (num)

          Check if argument is an integer (non-complex).

   IsNonNegativeInteger

IsNonNegativeInteger (num)

          Check if argument is a non-negative real integer. That
          is, either a positive integer or zero.

   IsPositiveInteger

IsPositiveInteger (num)

          Aliases: IsNaturalNumber

          Check if argument is a positive real integer. Note that
          we accept the convention that 0 is not a natural number.

   IsRational

IsRational (num)

          Check if argument is a rational number (non-complex). Of
          course rational simply means "not stored as a floating
          point number."

   IsReal

IsReal (num)

          Check if argument is a real number.

   Numerator

Numerator (x)

          Get the numerator of a rational number.

          See Wikipedia for more information.

   Re

Re (z)

          Aliases: RealPart

          Get the real part of a complex number. For example
          Re(3+4i) yields 3.

          See Wikipedia for more information.

   Sign

Sign (x)

          Aliases: sign

          Return the sign of a number. That is returns -1 if value
          is negative, 0 if value is zero and 1 if value is
          positive. If x is a complex value then Sign returns the
          direction or 0.

   ceil

ceil (x)

          Aliases: Ceiling

          Get the lowest integer more than or equal to n.
          Examples:

genius> ceil(1.1)
= 2
genius> ceil(-1.1)
= -1

          Note that you should be careful and notice that floating
          point numbers are stored in binary and so may not be
          what you expect. For example ceil(420/4.2) returns 101
          instead of the expected 100. This is because 4.2 is
          actually very slightly less than 4.2. Use rational
          representation 42/10 if you want exact arithmetic.

   exp

exp (x)

          The exponential function. This is the function e^x where
          e is the base of the natural logarithm.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   float

float (x)

          Make number a floating point value. That is returns the
          floating point representation of the number x.

   floor

floor (x)

          Aliases: Floor

          Get the highest integer less than or equal to n.

   ln

ln (x)

          The natural logarithm, the logarithm to base e.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   log

log (x)

log (x,b)

          Logarithm of x base b (calls DiscreteLog if in modulo
          mode), if base is not given, e is used.

   log10

log10 (x)

          Logarithm of x base 10.

   log2

log2 (x)

          Aliases: lg

          Logarithm of x base 2.

   max

max (a,args...)

          Aliases: Max Maximum

          Returns the maximum of arguments or matrix.

   min

min (a,args...)

          Aliases: Min Minimum

          Returns the minimum of arguments or matrix.

   rand

rand (size...)

          Generate random float in the range [0,1). If size is
          given then a matrix (if two numbers are specified) or
          vector (if one number is specified) of the given size
          returned.

   randint

randint (max,size...)

          Generate random integer in the range [0,max). If size is
          given then a matrix (if two numbers are specified) or
          vector (if one number is specified) of the given size
          returned. For example,

genius> randint(4)
= 3
genius> randint(4,2)
=
[0      1]
genius> randint(4,2,3)
=
[2      2       1
 0      0       3]

   round

round (x)

          Aliases: Round

          Round a number.

   sqrt

sqrt (x)

          Aliases: SquareRoot

          The square root. When operating modulo some integer will
          return either a null or a vector of the square roots.
          Examples:

genius> sqrt(2)
= 1.41421356237
genius> sqrt(-1)
= 1i
genius> sqrt(4) mod 7
=
[2      5]
genius> 2*2 mod 7
= 4

          See Wikipedia or Planetmath for more information.

   trunc

trunc (x)

          Aliases: Truncate IntegerPart

          Truncate number to an integer (return the integer part).
     __________________________________________________________

11.6. Trigonometry

   acos

acos (x)

          Aliases: arccos

          The arccos (inverse cos) function.

   acosh

acosh (x)

          Aliases: arccosh

          The arccosh (inverse cosh) function.

   acot

acot (x)

          Aliases: arccot

          The arccot (inverse cot) function.

   acoth

acoth (x)

          Aliases: arccoth

          The arccoth (inverse coth) function.

   acsc

acsc (x)

          Aliases: arccsc

          The inverse cosecant function.

   acsch

acsch (x)

          Aliases: arccsch

          The inverse hyperbolic cosecant function.

   asec

asec (x)

          Aliases: arcsec

          The inverse secant function.

   asech

asech (x)

          Aliases: arcsech

          The inverse hyperbolic secant function.

   asin

asin (x)

          Aliases: arcsin

          The arcsin (inverse sin) function.

   asinh

asinh (x)

          Aliases: arcsinh

          The arcsinh (inverse sinh) function.

   atan

atan (x)

          Aliases: arctan

          Calculates the arctan (inverse tan) function.

          See Wikipedia or Mathworld for more information.

   atanh

atanh (x)

          Aliases: arctanh

          The arctanh (inverse tanh) function.

   atan2

atan2 (y, x)

          Aliases: arctan2

          Calculates the arctan2 function. If x>0 then it returns
          atan(y/x). If x<0 then it returns sign(y) * (pi -
          atan(|y/x|). When x=0 it returns sign(y) * pi/2.
          atan2(0,0) returns 0 rather than failing.

          See Wikipedia or Mathworld for more information.

   cos

cos (x)

          Calculates the cosine function.

          See Wikipedia or Planetmath for more information.

   cosh

cosh (x)

          Calculates the hyperbolic cosine function.

          See Wikipedia or Planetmath for more information.

   cot

cot (x)

          The cotangent function.

          See Wikipedia or Planetmath for more information.

   coth

coth (x)

          The hyperbolic cotangent function.

          See Wikipedia or Planetmath for more information.

   csc

csc (x)

          The cosecant function.

          See Wikipedia or Planetmath for more information.

   csch

csch (x)

          The hyperbolic cosecant function.

          See Wikipedia or Planetmath for more information.

   sec

sec (x)

          The secant function.

          See Wikipedia or Planetmath for more information.

   sech

sech (x)

          The hyperbolic secant function.

          See Wikipedia or Planetmath for more information.

   sin

sin (x)

          Calculates the sine function.

          See Wikipedia or Planetmath for more information.

   sinh

sinh (x)

          Calculates the hyperbolic sine function.

          See Wikipedia or Planetmath for more information.

   tan

tan (x)

          Calculates the tan function.

          See Wikipedia or Planetmath for more information.

   tanh

tanh (x)

          The hyperbolic tangent function.

          See Wikipedia or Planetmath for more information.
     __________________________________________________________

11.7. Number Theory

   AreRelativelyPrime

AreRelativelyPrime (a,b)

          Are the real integers a and b relatively prime? Returns
          true or false.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   BernoulliNumber

BernoulliNumber (n)

          Return the nth Bernoulli number.

          See Wikipedia or Mathworld for more information.

   ChineseRemainder

ChineseRemainder (a,m)

          Aliases: CRT

          Find the x that solves the system given by the vector a
          and modulo the elements of m, using the Chinese
          Remainder Theorem.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   CombineFactorizations

CombineFactorizations (a,b)

          Given two factorizations, give the factorization of the
          product.

          See Factorize.

   ConvertFromBase

ConvertFromBase (v,b)

          Convert a vector of values indicating powers of b to a
          number.

   ConvertToBase

ConvertToBase (n,b)

          Convert a number to a vector of powers for elements in
          base b.

   DiscreteLog

DiscreteLog (n,b,q)

          Find discrete log of n base b in F[q], the finite field
          of order q, where q is a prime, using the
          Silver-Pohlig-Hellman algorithm.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   Divides

Divides (m,n)

          Checks divisibility (if m divides n).

   EulerPhi

EulerPhi (n)

          Compute the Euler phi function for n, that is the number
          of integers between 1 and n relatively prime to n.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   ExactDivision

ExactDivision (n,d)

          Return n/d but only if d divides n. If d does not divide
          n then this function returns garbage. This is a lot
          faster for very large numbers than the operation n/d,
          but of course only useful if you know that the division
          is exact.

   Factorize

Factorize (n)

          Return factorization of a number as a matrix. The first
          row is the primes in the factorization (including 1) and
          the second row are the powers. So for example:

genius> Factorize(11*11*13)
=
[1      11      13
 1      2       1]

          See Wikipedia for more information.

   Factors

Factors (n)

          Return all factors of n in a vector. This includes all
          the non-prime factors as well. It includes 1 and the
          number itself. So for example to print all the perfect
          numbers (those that are sums of their factors) up to the
          number 1000 you could do (this is of course very
          inefficient)

for n=1 to 1000 do (
    if MatrixSum (Factors(n)) == 2*n then
        print(n)
)

   FermatFactorization

FermatFactorization (n,tries)

          Attempt Fermat factorization of n into (t-s)*(t+s),
          returns t and s as a vector if possible, null otherwise.
          tries specifies the number of tries before giving up.

          This is a fairly good factorization if your number is
          the product of two factors that are very close to each
          other.

          See Wikipedia for more information.

   FindPrimitiveElementMod

FindPrimitiveElementMod (q)

          Find the first primitive element in F[q], the finite
          group of order q. Of course q must be a prime.

   FindRandomPrimitiveElementMod

FindRandomPrimitiveElementMod (q)

          Find a random primitive element in F[q], the finite
          group of order q (q must be a prime).

   IndexCalculus

IndexCalculus (n,b,q,S)

          Compute discrete log base b of n in F[q], the finite
          group of order q (q a prime), using the factor base S. S
          should be a column of primes possibly with second column
          precalculated by IndexCalculusPrecalculation.

   IndexCalculusPrecalculation

IndexCalculusPrecalculation (b,q,S)

          Run the precalculation step of IndexCalculus for
          logarithms base b in F[q], the finite group of order q
          (q a prime), for the factor base S (where S is a column
          vector of primes). The logs will be precalculated and
          returned in the second column.

   IsEven

IsEven (n)

          Tests if an integer is even.

   IsMersennePrimeExponent

IsMersennePrimeExponent (p)

          Tests if a positive integer p is a Mersenne prime
          exponent. That is if 2^p-1 is a prime. It does this by
          looking it up in a table of known values, which is
          relatively short. See also MersennePrimeExponents and
          LucasLehmer.

          See Wikipedia, Planetmath, Mathworld or GIMPS for more
          information.

   IsNthPower

IsNthPower (m,n)

          Tests if a rational number m is a perfect nth power. See
          also IsPerfectPower and IsPerfectSquare.

   IsOdd

IsOdd (n)

          Tests if an integer is odd.

   IsPerfectPower

IsPerfectPower (n)

          Check an integer for being any perfect power, a^b.

   IsPerfectSquare

IsPerfectSquare (n)

          Check an integer for being a perfect square of an
          integer. The number must be an integer. Negative
          integers are of course never perfect squares of
          integers.

   IsPrime

IsPrime (n)

          Tests primality of integers, for numbers less than
          2.5e10 the answer is deterministic (if Riemann
          hypothesis is true). For numbers larger, the probability
          of a false positive depends on IsPrimeMillerRabinReps.
          That is the probability of false positive is 1/4 to the
          power IsPrimeMillerRabinReps. The default value of 22
          yields a probability of about 5.7e-14.

          If false is returned, you can be sure that the number is
          a composite. If you want to be absolutely sure that you
          have a prime you can use MillerRabinTestSure but it may
          take a lot longer.

          See Planetmath or Mathworld for more information.

   IsPrimitiveMod

IsPrimitiveMod (g,q)

          Check if g is primitive in F[q], the finite group of
          order q, where q is a prime. If q is not prime results
          are bogus.

   IsPrimitiveModWithPrimeFactors

IsPrimitiveModWithPrimeFactors (g,q,f)

          Check if g is primitive in F[q], the finite group of
          order q, where q is a prime and f is a vector of prime
          factors of q-1. If q is not prime results are bogus.

   IsPseudoprime

IsPseudoprime (n,b)

          If n is a pseudoprime base b but not a prime, that is if
          b^(n-1) == 1 mod n. This calls the PseudoprimeTest

   IsStrongPseudoprime

IsStrongPseudoprime (n,b)

          Test if n is a strong pseudoprime to base b but not a
          prime.

   Jacobi

Jacobi (a,b)

          Aliases: JacobiSymbol

          Calculate the Jacobi symbol (a/b) (b should be odd).

   JacobiKronecker

JacobiKronecker (a,b)

          Aliases: JacobiKroneckerSymbol

          Calculate the Jacobi symbol (a/b) with the Kronecker
          extension (a/2)=(2/a) when a odd, or (a/2)=0 when a
          even.

   LeastAbsoluteResidue

LeastAbsoluteResidue (a,n)

          Return the residue of a mod n with the least absolute
          value (in the interval -n/2 to n/2).

   Legendre

Legendre (a,p)

          Aliases: LegendreSymbol

          Calculate the Legendre symbol (a/p).

          See Planetmath or Mathworld for more information.

   LucasLehmer

LucasLehmer (p)

          Test if 2^p-1 is a Mersenne prime using the Lucas-Lehmer
          test. See also MersennePrimeExponents and
          IsMersennePrimeExponent.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   LucasNumber

LucasNumber (n)

          Returns the nth Lucas number.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   MaximalPrimePowerFactors

MaximalPrimePowerFactors (n)

          Return all maximal prime power factors of a number.

   MersennePrimeExponents

MersennePrimeExponents

          A vector of known Mersenne prime exponents, that is a
          list of positive integers p such that 2^p-1 is a prime.
          See also IsMersennePrimeExponent and LucasLehmer.

          See Wikipedia, Planetmath, Mathworld or GIMPS for more
          information.

   MillerRabinTest

MillerRabinTest (n,reps)

          Use the Miller-Rabin primality test on n, reps number of
          times. The probability of false positive is (1/4)^reps.
          It is probably usually better to use IsPrime since that
          is faster and better on smaller integers.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   MillerRabinTestSure

MillerRabinTestSure (n)

          Use the Miller-Rabin primality test on n with enough
          bases that assuming the Generalized Riemann Hypothesis
          the result is deterministic.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   ModInvert

ModInvert (n,m)

          Returns inverse of n mod m.

          See Mathworld for more information.

   MoebiusMu

MoebiusMu (n)

          Return the Moebius mu function evaluated in n. That is,
          it returns 0 if n is not a product of distinct primes
          and (-1)^k if it is a product of k distinct primes.

          See Planetmath or Mathworld for more information.

   NextPrime

NextPrime (n)

          Returns the least prime greater than n. Negatives of
          primes are considered prime and so to get the previous
          prime you can use -NextPrime(-n).

          This function uses the GMPs mpz_nextprime, which in turn
          uses the probabilistic Miller-Rabin test (See also
          MillerRabinTest). The probability of false positive is
          not tunable, but is low enough for all practical
          purposes.

          See Planetmath or Mathworld for more information.

   PadicValuation

PadicValuation (n,p)

          Returns the p-adic valuation (number of trailing zeros
          in base p).

          See Wikipedia or Planetmath for more information.

   PowerMod

PowerMod (a,b,m)

          Compute a^b mod m. The b's power of a modulo m. It is
          not necessary to use this function as it is
          automatically used in modulo mode. Hence a^b mod m is
          just as fast.

   Prime

Prime (n)

          Aliases: prime

          Return the nth prime (up to a limit).

          See Planetmath or Mathworld for more information.

   PrimeFactors

PrimeFactors (n)

          Return all prime factors of a number as a vector.

          See Wikipedia or Mathworld for more information.

   PseudoprimeTest

PseudoprimeTest (n,b)

          Pseudoprime test, returns true if and only if b^(n-1) ==
          1 mod n

          See Planetmath or Mathworld for more information.

   RemoveFactor

RemoveFactor (n,m)

          Removes all instances of the factor m from the number n.
          That is divides by the largest power of m, that divides
          n.

          See Planetmath or Mathworld for more information.

   SilverPohligHellmanWithFactorization

SilverPohligHellmanWithFactorization (n,b,q,f)

          Find discrete log of n base b in F[q], the finite group
          of order q, where q is a prime using the
          Silver-Pohlig-Hellman algorithm, given f being the
          factorization of q-1.

   SqrtModPrime

SqrtModPrime (n,p)

          Find square root of n modulo p (where p is a prime).
          Null is returned if not a quadratic residue.

          See Planetmath or Mathworld for more information.

   StrongPseudoprimeTest

StrongPseudoprimeTest (n,b)

          Run the strong pseudoprime test base b on n.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   gcd

gcd (a,args...)

          Aliases: GCD

          Greatest common divisor of integers. You can enter as
          many integers as you want in the argument list, or you
          can give a vector or a matrix of integers. If you give
          more than one matrix of the same size then GCD is done
          element by element.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   lcm

lcm (a,args...)

          Aliases: LCM

          Least common multiplier of integers. You can enter as
          many integers as you want in the argument list, or you
          can give a vector or a matrix of integers. If you give
          more than one matrix of the same size then LCM is done
          element by element.

          See Wikipedia, Planetmath, or Mathworld for more
          information.
     __________________________________________________________

11.8. Matrix Manipulation

   ApplyOverMatrix

ApplyOverMatrix (a,func)

          Apply a function over all entries of a matrix and return
          a matrix of the results.

   ApplyOverMatrix2

ApplyOverMatrix2 (a,b,func)

          Apply a function over all entries of 2 matrices (or 1
          value and 1 matrix) and return a matrix of the results.

   ColumnsOf

ColumnsOf (M)

          Gets the columns of a matrix as a horizontal vector.

   ComplementSubmatrix

ComplementSubmatrix (m,r,c)

          Remove column(s) and row(s) from a matrix.

   CompoundMatrix

CompoundMatrix (k,A)

          Calculate the kth compound matrix of A.

   CountZeroColumns

CountZeroColumns (M)

          Count the number of zero columns in a matrix. For
          example, once you column-reduce a matrix, you can use
          this to find the nullity. See cref and Nullity.

   DeleteColumn

DeleteColumn (M,col)

          Delete a column of a matrix.

   DeleteRow

DeleteRow (M,row)

          Delete a row of a matrix.

   DiagonalOf

DiagonalOf (M)

          Gets the diagonal entries of a matrix as a column
          vector.

          See Wikipedia for more information.

   DotProduct

DotProduct (u,v)

          Get the dot product of two vectors. The vectors must be
          of the same size. No conjugates are taken so this is a
          bilinear form even if working over the complex numbers;
          This is the bilinear scalar product not the sesquilinear
          scalar product. See HermitianProduct for the standard
          sesquilinear inner product.

          See Wikipedia or Planetmath for more information.

   ExpandMatrix

ExpandMatrix (M)

          Expands a matrix just like we do on unquoted matrix
          input. That is we expand any internal matrices as
          blocks. This is a way to construct matrices out of
          smaller ones and this is normally done automatically on
          input unless the matrix is quoted.

   HermitianProduct

HermitianProduct (u,v)

          Aliases: InnerProduct

          Get the Hermitian product of two vectors. The vectors
          must be of the same size. This is a sesquilinear form
          using the identity matrix.

          See Wikipedia or Mathworld for more information.

   I

I (n)

          Aliases: eye

          Return an identity matrix of a given size, that is n by
          n. If n is zero, returns null.

          See Wikipedia or Planetmath for more information.

   IndexComplement

IndexComplement (vec,msize)

          Return the index complement of a vector of indexes.
          Everything is one based. For example for vector [2,3]
          and size 5, we return [1,4,5]. If msize is 0, we always
          return null.

   IsDiagonal

IsDiagonal (M)

          Is a matrix diagonal.

          See Wikipedia or Planetmath for more information.

   IsIdentity

IsIdentity (x)

          Check if a matrix is the identity matrix. Automatically
          returns false if the matrix is not square. Also works on
          numbers, in which case it is equivalent to x==1. When x
          is null (we could think of that as a 0 by 0 matrix), no
          error is generated and false is returned.

   IsLowerTriangular

IsLowerTriangular (M)

          Is a matrix lower triangular. That is, are all the
          entries above the diagonal zero.

   IsMatrixInteger

IsMatrixInteger (M)

          Check if a matrix is a matrix of integers (non-complex).

   IsMatrixNonnegative

IsMatrixNonnegative (M)

          Check if a matrix is non-negative, that is if each
          element is non-negative. Do not confuse positive
          matrices with positive semi-definite matrices.

          See Wikipedia for more information.

   IsMatrixPositive

IsMatrixPositive (M)

          Check if a matrix is positive, that is if each element
          is positive (and hence real). In particular, no element
          is 0. Do not confuse positive matrices with positive
          definite matrices.

          See Wikipedia for more information.

   IsMatrixRational

IsMatrixRational (M)

          Check if a matrix is a matrix of rational (non-complex)
          numbers.

   IsMatrixReal

IsMatrixReal (M)

          Check if a matrix is a matrix of real (non-complex)
          numbers.

   IsMatrixSquare

IsMatrixSquare (M)

          Check if a matrix is square, that is its width is equal
          to its height.

   IsUpperTriangular

IsUpperTriangular (M)

          Is a matrix upper triangular? That is, a matrix is upper
          triangular if all the entries below the diagonal are
          zero.

   IsValueOnly

IsValueOnly (M)

          Check if a matrix is a matrix of numbers only. Many
          internal functions make this check. Values can be any
          number including complex numbers.

   IsVector

IsVector (v)

          Is argument a horizontal or a vertical vector. Genius
          does not distinguish between a matrix and a vector and a
          vector is just a 1 by n or n by 1 matrix.

   IsZero

IsZero (x)

          Check if a matrix is composed of all zeros. Also works
          on numbers, in which case it is equivalent to x==0. When
          x is null (we could think of that as a 0 by 0 matrix),
          no error is generated and true is returned as the
          condition is vacuous.

   LowerTriangular

LowerTriangular (M)

          Returns a copy of the matrix M with all the entries
          above the diagonal set to zero.

   MakeDiagonal

MakeDiagonal (v,arg...)

          Aliases: diag

          Make diagonal matrix from a vector. Alternatively you
          can pass in the values to put on the diagonal as
          arguments. So MakeDiagonal([1,2,3]) is the same as
          MakeDiagonal(1,2,3).

          See Wikipedia or Planetmath for more information.

   MakeVector

MakeVector (A)

          Make column vector out of matrix by putting columns
          above each other. Returns null when given null.

   MatrixProduct

MatrixProduct (A)

          Calculate the product of all elements in a matrix or
          vector. That is we multiply all the elements and return
          a number that is the product of all the elements.

   MatrixSum

MatrixSum (A)

          Calculate the sum of all elements in a matrix or vector.
          That is we add all the elements and return a number that
          is the sum of all the elements.

   MatrixSumSquares

MatrixSumSquares (A)

          Calculate the sum of squares of all elements in a matrix
          or vector.

   NonzeroColumns

NonzeroColumns (M)

          Returns a row vector of the indices of nonzero columns
          in the matrix M.

          Version 1.0.18 onwards.

   NonzeroElements

NonzeroElements (v)

          Returns a row vector of the indices of nonzero elements
          in the vector v.

          Version 1.0.18 onwards.

   OuterProduct

OuterProduct (u,v)

          Get the outer product of two vectors. That is, suppose
          that u and v are vertical vectors, then the outer
          product is v * u.'.

   ReverseVector

ReverseVector (v)

          Reverse elements in a vector. Return null if given null

   RowSum

RowSum (m)

          Calculate sum of each row in a matrix and return a
          vertical vector with the result.

   RowSumSquares

RowSumSquares (m)

          Calculate sum of squares of each row in a matrix and
          return a vertical vector with the results.

   RowsOf

RowsOf (M)

          Gets the rows of a matrix as a vertical vector. Each
          element of the vector is a horizontal vector that is the
          corresponding row of M. This function is useful if you
          wish to loop over the rows of a matrix. For example, as
          for r in RowsOf(M) do something(r).

   SetMatrixSize

SetMatrixSize (M,rows,columns)

          Make new matrix of given size from old one. That is, a
          new matrix will be returned to which the old one is
          copied. Entries that don't fit are clipped and extra
          space is filled with zeros. If rows or columns are zero
          then null is returned.

   ShuffleVector

ShuffleVector (v)

          Shuffle elements in a vector. Return null if given null.

          Version 1.0.13 onwards.

   SortVector

SortVector (v)

          Sort vector elements in an increasing order.

   StripZeroColumns

StripZeroColumns (M)

          Removes any all-zero columns of M.

   StripZeroRows

StripZeroRows (M)

          Removes any all-zero rows of M.

   Submatrix

Submatrix (m,r,c)

          Return column(s) and row(s) from a matrix. This is just
          equivalent to m@(r,c). r and c should be vectors of rows
          and columns (or single numbers if only one row or column
          is needed).

   SwapRows

SwapRows (m,row1,row2)

          Swap two rows in a matrix.

   UpperTriangular

UpperTriangular (M)

          Returns a copy of the matrix M with all the entries
          below the diagonal set to zero.

   columns

columns (M)

          Get the number of columns of a matrix.

   elements

elements (M)

          Get the total number of elements of a matrix. This is
          the number of columns times the number of rows.

   ones

ones (rows,columns...)

          Make an matrix of all ones (or a row vector if only one
          argument is given). Returns null if either rows or
          columns are zero.

   rows

rows (M)

          Get the number of rows of a matrix.

   zeros

zeros (rows,columns...)

          Make a matrix of all zeros (or a row vector if only one
          argument is given). Returns null if either rows or
          columns are zero.
     __________________________________________________________

11.9. Linear Algebra

   AuxiliaryUnitMatrix

AuxiliaryUnitMatrix (n)

          Get the auxiliary unit matrix of size n. This is a
          square matrix with that is all zero except the
          superdiagonal being all ones. It is the Jordan block
          matrix of one zero eigenvalue.

          See Planetmath or Mathworld for more information on
          Jordan Canonical Form.

   BilinearForm

BilinearForm (v,A,w)

          Evaluate (v,w) with respect to the bilinear form given
          by the matrix A.

   BilinearFormFunction

BilinearFormFunction (A)

          Return a function that evaluates two vectors with
          respect to the bilinear form given by A.

   CharacteristicPolynomial

CharacteristicPolynomial (M)

          Aliases: CharPoly

          Get the characteristic polynomial as a vector. That is,
          return the coefficients of the polynomial starting with
          the constant term. This is the polynomial defined by
          det(M-xI). The roots of this polynomial are the
          eigenvalues of M. See also
          CharacteristicPolynomialFunction.

          See Wikipedia or Planetmath for more information.

   CharacteristicPolynomialFunction

CharacteristicPolynomialFunction (M)

          Get the characteristic polynomial as a function. This is
          the polynomial defined by det(M-xI). The roots of this
          polynomial are the eigenvalues of M. See also
          CharacteristicPolynomial.

          See Wikipedia or Planetmath for more information.

   ColumnSpace

ColumnSpace (M)

          Get a basis matrix for the columnspace of a matrix. That
          is, return a matrix whose columns are the basis for the
          column space of M. That is the space spanned by the
          columns of M.

          See Wikipedia for more information.

   CommutationMatrix

CommutationMatrix (m, n)

          Return the commutation matrix K(m,n), which is the
          unique m*n by m*n matrix such that K(m,n) *
          MakeVector(A) = MakeVector(A.') for all m by n matrices
          A.

   CompanionMatrix

CompanionMatrix (p)

          Companion matrix of a polynomial (as vector).

   ConjugateTranspose

ConjugateTranspose (M)

          Conjugate transpose of a matrix (adjoint). This is the
          same as the ' operator.

          See Wikipedia or Planetmath for more information.

   Convolution

Convolution (a,b)

          Aliases: convol

          Calculate convolution of two horizontal vectors.

   ConvolutionVector

ConvolutionVector (a,b)

          Calculate convolution of two horizontal vectors. Return
          result as a vector and not added together.

   CrossProduct

CrossProduct (v,w)

          CrossProduct of two vectors in R^3 as a column vector.

          See Wikipedia for more information.

   DeterminantalDivisorsInteger

DeterminantalDivisorsInteger (M)

          Get the determinantal divisors of an integer matrix.

   DirectSum

DirectSum (M,N...)

          Direct sum of matrices.

          See Wikipedia for more information.

   DirectSumMatrixVector

DirectSumMatrixVector (v)

          Direct sum of a vector of matrices.

          See Wikipedia for more information.

   Eigenvalues

Eigenvalues (M)

          Aliases: eig

          Get the eigenvalues of a square matrix. Currently only
          works for matrices of size up to 4 by 4, or for
          triangular matrices (for which the eigenvalues are on
          the diagonal).

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   Eigenvectors

Eigenvectors (M)

Eigenvectors (M, &eigenvalues)

Eigenvectors (M, &eigenvalues, &multiplicities)

          Get the eigenvectors of a square matrix. Optionally get
          also the eigenvalues and their algebraic multiplicities.
          Currently only works for matrices of size up to 2 by 2.

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   GramSchmidt

GramSchmidt (v,B...)

          Apply the Gram-Schmidt process (to the columns) with
          respect to inner product given by B. If B is not given
          then the standard Hermitian product is used. B can
          either be a sesquilinear function of two arguments or it
          can be a matrix giving a sesquilinear form. The vectors
          will be made orthonormal with respect to B.

          See Wikipedia or Planetmath for more information.

   HankelMatrix

HankelMatrix (c,r)

          Hankel matrix, a matrix whose skew-diagonals are
          constant. c is the first row and r is the last column.
          It is assumed that both arguments are vectors and the
          last element of c is the same as the first element of r.

          See Wikipedia for more information.

   HilbertMatrix

HilbertMatrix (n)

          Hilbert matrix of order n.

          See Wikipedia or Planetmath for more information.

   Image

Image (T)

          Get the image (columnspace) of a linear transform.

          See Wikipedia for more information.

   InfNorm

InfNorm (v)

          Get the Inf Norm of a vector, sometimes called the sup
          norm or the max norm.

   InvariantFactorsInteger

InvariantFactorsInteger (M)

          Get the invariant factors of a square integer matrix.

   InverseHilbertMatrix

InverseHilbertMatrix (n)

          Inverse Hilbert matrix of order n.

          See Wikipedia or Planetmath for more information.

   IsHermitian

IsHermitian (M)

          Is a matrix Hermitian. That is, is it equal to its
          conjugate transpose.

          See Wikipedia or Planetmath for more information.

   IsInSubspace

IsInSubspace (v,W)

          Test if a vector is in a subspace.

   IsInvertible

IsInvertible (n)

          Is a matrix (or number) invertible (Integer matrix is
          invertible if and only if it is invertible over the
          integers).

   IsInvertibleField

IsInvertibleField (n)

          Is a matrix (or number) invertible over a field.

   IsNormal

IsNormal (M)

          Is M a normal matrix. That is, does M*M' == M'*M.

          See Planetmath or Mathworld for more information.

   IsPositiveDefinite

IsPositiveDefinite (M)

          Is M a Hermitian positive definite matrix. That is if
          HermitianProduct(M*v,v) is always strictly positive for
          any vector v. M must be square and Hermitian to be
          positive definite. The check that is performed is that
          every principal submatrix has a non-negative
          determinant. (See HermitianProduct)

          Note that some authors (for example Mathworld) do not
          require that M be Hermitian, and then the condition is
          on the real part of the inner product, but we do not
          take this view. If you wish to perform this check, just
          check the Hermitian part of the matrix M as follows:
          IsPositiveDefinite(M+M').

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   IsPositiveSemidefinite

IsPositiveSemidefinite (M)

          Is M a Hermitian positive semidefinite matrix. That is
          if HermitianProduct(M*v,v) is always non-negative for
          any vector v. M must be square and Hermitian to be
          positive semidefinite. The check that is performed is
          that every principal submatrix has a non-negative
          determinant. (See HermitianProduct)

          Note that some authors do not require that M be
          Hermitian, and then the condition is on the real part of
          the inner product, but we do not take this view. If you
          wish to perform this check, just check the Hermitian
          part of the matrix M as follows:
          IsPositiveSemidefinite(M+M').

          See Planetmath or Mathworld for more information.

   IsSkewHermitian

IsSkewHermitian (M)

          Is a matrix skew-Hermitian. That is, is the conjugate
          transpose equal to negative of the matrix.

          See Planetmath for more information.

   IsUnitary

IsUnitary (M)

          Is a matrix unitary? That is, does M'*M and M*M' equal
          the identity.

          See Planetmath or Mathworld for more information.

   JordanBlock

JordanBlock (n,lambda)

          Aliases: J

          Get the Jordan block corresponding to the eigenvalue
          lambda with multiplicity n.

          See Planetmath or Mathworld for more information.

   Kernel

Kernel (T)

          Get the kernel (nullspace) of a linear transform.

          (See NullSpace)

   KroneckerProduct

KroneckerProduct (M, N)

          Aliases: TensorProduct

          Compute the Kronecker product (tensor product in
          standard basis) of two matrices.

          See Wikipedia, Planetmath or Mathworld for more
          information.

          Version 1.0.18 onwards.

   LUDecomposition

LUDecomposition (A, L, U)

          Get the LU decomposition of A, that is find a lower
          triangular matrix and upper triangular matrix whose
          product is A. Store the result in the L and U, which
          should be references. It returns true if successful. For
          example suppose that A is a square matrix, then after
          running:

genius> LUDecomposition(A,&L,&U)

          You will have the lower matrix stored in a variable
          called L and the upper matrix in a variable called U.

          This is the LU decomposition of a matrix aka Crout
          and/or Cholesky reduction. (ISBN 0-201-11577-8
          pp.99-103) The upper triangular matrix features a
          diagonal of values 1 (one). This is not Doolittle's
          Method, which features the 1's diagonal on the lower
          matrix.

          Not all matrices have LU decompositions, for example
          [0,1;1,0] does not and this function returns false in
          this case and sets L and U to null.

          See Wikipedia, Planetmath or Mathworld for more
          information.

   Minor

Minor (M,i,j)

          Get the i-j minor of a matrix.

          See Planetmath for more information.

   NonPivotColumns

NonPivotColumns (M)

          Return the columns that are not the pivot columns of a
          matrix.

   Norm

Norm (v,p...)

          Aliases: norm

          Get the p Norm (or 2 Norm if no p is supplied) of a
          vector.

   NullSpace

NullSpace (T)

          Get the nullspace of a matrix. That is the kernel of the
          linear mapping that the matrix represents. This is
          returned as a matrix whose column space is the nullspace
          of T.

          See Planetmath for more information.

   Nullity

Nullity (M)

          Aliases: nullity

          Get the nullity of a matrix. That is, return the
          dimension of the nullspace; the dimension of the kernel
          of M.

          See Planetmath for more information.

   OrthogonalComplement

OrthogonalComplement (M)

          Get the orthogonal complement of the columnspace.

   PivotColumns

PivotColumns (M)

          Return pivot columns of a matrix, that is columns that
          have a leading 1 in row reduced form. Also returns the
          row where they occur.

   Projection

Projection (v,W,B...)

          Projection of vector v onto subspace W with respect to
          inner product given by B. If B is not given then the
          standard Hermitian product is used. B can either be a
          sesquilinear function of two arguments or it can be a
          matrix giving a sesquilinear form.

   QRDecomposition

QRDecomposition (A, Q)

          Get the QR decomposition of a square matrix A, returns
          the upper triangular matrix R and sets Q to the
          orthogonal (unitary) matrix. Q should be a reference or
          null if you don't want any return. For example:

genius> R = QRDecomposition(A,&Q)

          You will have the upper triangular matrix stored in a
          variable called R and the orthogonal (unitary) matrix
          stored in Q.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   RayleighQuotient

RayleighQuotient (A,x)

          Return the Rayleigh quotient (also called the
          Rayleigh-Ritz quotient or ratio) of a matrix and a
          vector.

          See Planetmath for more information.

   RayleighQuotientIteration

RayleighQuotientIteration (A,x,epsilon,maxiter,vecref)

          Find eigenvalues of A using the Rayleigh quotient
          iteration method. x is a guess at a eigenvector and
          could be random. It should have nonzero imaginary part
          if it will have any chance at finding complex
          eigenvalues. The code will run at most maxiter
          iterations and return null if we cannot get within an
          error of epsilon. vecref should either be null or a
          reference to a variable where the eigenvector should be
          stored.

          See Planetmath for more information on Rayleigh
          quotient.

   Rank

Rank (M)

          Aliases: rank

          Get the rank of a matrix.

          See Planetmath for more information.

   RosserMatrix

RosserMatrix ()

          Returns the Rosser matrix, which is a classic symmetric
          eigenvalue test problem.

   Rotation2D

Rotation2D (angle)

          Aliases: RotationMatrix

          Return the matrix corresponding to rotation around
          origin in R^2.

   Rotation3DX

Rotation3DX (angle)

          Return the matrix corresponding to rotation around
          origin in R^3 about the x-axis.

   Rotation3DY

Rotation3DY (angle)

          Return the matrix corresponding to rotation around
          origin in R^3 about the y-axis.

   Rotation3DZ

Rotation3DZ (angle)

          Return the matrix corresponding to rotation around
          origin in R^3 about the z-axis.

   RowSpace

RowSpace (M)

          Get a basis matrix for the rowspace of a matrix.

   SesquilinearForm

SesquilinearForm (v,A,w)

          Evaluate (v,w) with respect to the sesquilinear form
          given by the matrix A.

   SesquilinearFormFunction

SesquilinearFormFunction (A)

          Return a function that evaluates two vectors with
          respect to the sesquilinear form given by A.

   SmithNormalFormField

SmithNormalFormField (A)

          Returns the Smith normal form of a matrix over fields
          (will end up with 1's on the diagonal).

          See Wikipedia for more information.

   SmithNormalFormInteger

SmithNormalFormInteger (M)

          Return the Smith normal form for square integer matrices
          over integers.

          See Wikipedia for more information.

   SolveLinearSystem

SolveLinearSystem (M,V,args...)

          Solve linear system Mx=V, return solution V if there is
          a unique solution, null otherwise. Extra two reference
          parameters can optionally be used to get the reduced M
          and V.

   ToeplitzMatrix

ToeplitzMatrix (c, r...)

          Return the Toeplitz matrix constructed given the first
          column c and (optionally) the first row r. If only the
          column c is given then it is conjugated and the
          nonconjugated version is used for the first row to give
          a Hermitian matrix (if the first element is real of
          course).

          See Wikipedia or Planetmath for more information.

   Trace

Trace (M)

          Aliases: trace

          Calculate the trace of a matrix. That is the sum of the
          diagonal elements.

          See Wikipedia or Planetmath for more information.

   Transpose

Transpose (M)

          Transpose of a matrix. This is the same as the .'
          operator.

          See Wikipedia or Planetmath for more information.

   VandermondeMatrix

VandermondeMatrix (v)

          Aliases: vander

          Return the Vandermonde matrix.

          See Wikipedia for more information.

   VectorAngle

VectorAngle (v,w,B...)

          The angle of two vectors with respect to inner product
          given by B. If B is not given then the standard
          Hermitian product is used. B can either be a
          sesquilinear function of two arguments or it can be a
          matrix giving a sesquilinear form.

   VectorSpaceDirectSum

VectorSpaceDirectSum (M,N)

          The direct sum of the vector spaces M and N.

   VectorSubspaceIntersection

VectorSubspaceIntersection (M,N)

          Intersection of the subspaces given by M and N.

   VectorSubspaceSum

VectorSubspaceSum (M,N)

          The sum of the vector spaces M and N, that is {w |
          w=m+n, m in M, n in N}.

   adj

adj (m)

          Aliases: Adjugate

          Get the classical adjoint (adjugate) of a matrix.

   cref

cref (M)

          Aliases: CREF ColumnReducedEchelonForm

          Compute the Column Reduced Echelon Form.

   det

det (M)

          Aliases: Determinant

          Get the determinant of a matrix.

          See Wikipedia or Planetmath for more information.

   ref

ref (M)

          Aliases: REF RowEchelonForm

          Get the row echelon form of a matrix. That is, apply
          gaussian elimination but not backaddition to M. The
          pivot rows are divided to make all pivots 1.

          See Wikipedia or Planetmath for more information.

   rref

rref (M)

          Aliases: RREF ReducedRowEchelonForm

          Get the reduced row echelon form of a matrix. That is,
          apply gaussian elimination together with backaddition to
          M.

          See Wikipedia or Planetmath for more information.
     __________________________________________________________

11.10. Combinatorics

   Catalan

Catalan (n)

          Get nth Catalan number.

          See Planetmath for more information.

   Combinations

Combinations (k,n)

          Get all combinations of k numbers from 1 to n as a
          vector of vectors. (See also NextCombination)

          See Wikipedia for more information.

   DoubleFactorial

DoubleFactorial (n)

          Double factorial: n(n-2)(n-4)...

          See Planetmath for more information.

   Factorial

Factorial (n)

          Factorial: n(n-1)(n-2)...

          See Planetmath for more information.

   FallingFactorial

FallingFactorial (n,k)

          Falling factorial: (n)_k = n(n-1)...(n-(k-1))

          See Planetmath for more information.

   Fibonacci

Fibonacci (x)

          Aliases: fib

          Calculate nth Fibonacci number. That is the number
          defined recursively by Fibonacci(n) = Fibonacci(n-1) +
          Fibonacci(n-2) and Fibonacci(1) = Fibonacci(2) = 1.

          See Wikipedia or Planetmath or Mathworld for more
          information.

   FrobeniusNumber

FrobeniusNumber (v,arg...)

          Calculate the Frobenius number. That is calculate
          largest number that cannot be given as a non-negative
          integer linear combination of a given vector of
          non-negative integers. The vector can be given as
          separate numbers or a single vector. All the numbers
          given should have GCD of 1.

          See Wikipedia or Mathworld for more information.

   GaloisMatrix

GaloisMatrix (combining_rule)

          Galois matrix given a linear combining rule
          (a_1*x_1+...+a_n*x_n=x_(n+1)).

   GreedyAlgorithm

GreedyAlgorithm (n,v)

          Find the vector c of non-negative integers such that
          taking the dot product with v is equal to n. If not
          possible returns null. v should be given sorted in
          increasing order and should consist of non-negative
          integers.

          See Wikipedia or Mathworld for more information.

   HarmonicNumber

HarmonicNumber (n,r)

          Aliases: HarmonicH

          Harmonic Number, the nth harmonic number of order r.
          That is, it is the sum of 1/k^r for k from 1 to n.
          Equivalent to sum k = 1 to n do 1/k^r.

          See Wikipedia for more information.

   Hofstadter

Hofstadter (n)

          Hofstadter's function q(n) defined by q(1)=1, q(2)=1,
          q(n)=q(n-q(n-1))+q(n-q(n-2)).

          See Wikipedia for more information. The sequence is
          A005185 in OEIS.

   LinearRecursiveSequence

LinearRecursiveSequence (seed_values,combining_rule,n)

          Compute linear recursive sequence using Galois stepping.

   Multinomial

Multinomial (v,arg...)

          Calculate multinomial coefficients. Takes a vector of k
          non-negative integers and computes the multinomial
          coefficient. This corresponds to the coefficient in the
          homogeneous polynomial in k variables with the
          corresponding powers.

          The formula for Multinomial(a,b,c) can be written as:

(a+b+c)! / (a!b!c!)

          In other words, if we would have only two elements, then
          Multinomial(a,b) is the same thing as Binomial(a+b,a) or
          Binomial(a+b,b).

          See Wikipedia, Planetmath, or Mathworld for more
          information.

   NextCombination

NextCombination (v,n)

          Get combination that would come after v in call to
          combinations, first combination should be [1:k]. This
          function is useful if you have many combinations to go
          through and you don't want to waste memory to store them
          all.

          For example with Combinations you would normally write a
          loop like:

for n in Combinations (4,6) do (
  SomeFunction (n)
);

          But with NextCombination you would write something like:

n:=[1:4];
do (
  SomeFunction (n)
) while not IsNull(n:=NextCombination(n,6));

          See also Combinations.

          See Wikipedia for more information.

   Pascal

Pascal (i)

          Get the Pascal's triangle as a matrix. This will return
          an i+1 by i+1 lower diagonal matrix that is the Pascal's
          triangle after i iterations.

          See Planetmath for more information.

   Permutations

Permutations (k,n)

          Get all permutations of k numbers from 1 to n as a
          vector of vectors.

          See Mathworld or Wikipedia for more information.

   RisingFactorial

RisingFactorial (n,k)

          Aliases: Pochhammer

          (Pochhammer) Rising factorial: (n)_k =
          n(n+1)...(n+(k-1)).

          See Planetmath for more information.

   StirlingNumberFirst

StirlingNumberFirst (n,m)

          Aliases: StirlingS1

          Stirling number of the first kind.

          See Planetmath or Mathworld for more information.

   StirlingNumberSecond

StirlingNumberSecond (n,m)

          Aliases: StirlingS2

          Stirling number of the second kind.

          See Planetmath or Mathworld for more information.

   Subfactorial

Subfactorial (n)

          Subfactorial: n! times sum_{k=0}^n (-1)^k/k!.

   Triangular

Triangular (nth)

          Calculate the nth triangular number.

          See Planetmath for more information.

   nCr

nCr (n,r)

          Aliases: Binomial

          Calculate combinations, that is, the binomial
          coefficient. n can be any real number.

          See Planetmath for more information.

   nPr

nPr (n,r)

          Calculate the number of permutations of size r of
          numbers from 1 to n.

          See Mathworld or Wikipedia for more information.
     __________________________________________________________

11.11. Calculus

   CompositeSimpsonsRule

CompositeSimpsonsRule (f,a,b,n)

          Integration of f by Composite Simpson's Rule on the
          interval [a,b] with n subintervals with error of
          max(f'''')*h^4*(b-a)/180, note that n should be even.

          See Planetmath for more information.

   CompositeSimpsonsRuleTolerance

CompositeSimpsonsRuleTolerance (f,a,b,FourthDerivativeBound,Tolerance)

          Integration of f by Composite Simpson's Rule on the
          interval [a,b] with the number of steps calculated by
          the fourth derivative bound and the desired tolerance.

          See Planetmath for more information.

   Derivative

Derivative (f,x0)

          Attempt to calculate derivative by trying first
          symbolically and then numerically.

          See Wikipedia for more information.

   EvenPeriodicExtension

EvenPeriodicExtension (f,L)

          Return a function that is the even periodic extension of
          f with half period L. That is a function defined on the
          interval [0,L] extended to be even on [-L,L] and then
          extended to be periodic with period 2*L.

          See also OddPeriodicExtension and PeriodicExtension.

          Version 1.0.7 onwards.

   FourierSeriesFunction

FourierSeriesFunction (a,b,L)

          Return a function that is a Fourier series with the
          coefficients given by the vectors a (sines) and b
          (cosines). Note that a@(1) is the constant coefficient!
          That is, a@(n) refers to the term cos(x*(n-1)*pi/L),
          while b@(n) refers to the term sin(x*n*pi/L). Either a
          or b can be null.

          See Wikipedia or Mathworld for more information.

   InfiniteProduct

InfiniteProduct (func,start,inc)

          Try to calculate an infinite product for a single
          parameter function.

   InfiniteProduct2

InfiniteProduct2 (func,arg,start,inc)

          Try to calculate an infinite product for a double
          parameter function with func(arg,n).

   InfiniteSum

InfiniteSum (func,start,inc)

          Try to calculate an infinite sum for a single parameter
          function.

   InfiniteSum2

InfiniteSum2 (func,arg,start,inc)

          Try to calculate an infinite sum for a double parameter
          function with func(arg,n).

   IsContinuous

IsContinuous (f,x0)

          Try and see if a real-valued function is continuous at
          x0 by calculating the limit there.

   IsDifferentiable

IsDifferentiable (f,x0)

          Test for differentiability by approximating the left and
          right limits and comparing.

   LeftLimit

LeftLimit (f,x0)

          Calculate the left limit of a real-valued function at
          x0.

   Limit

Limit (f,x0)

          Calculate the limit of a real-valued function at x0.
          Tries to calculate both left and right limits.

   MidpointRule

MidpointRule (f,a,b,n)

          Integration by midpoint rule.

   NumericalDerivative

NumericalDerivative (f,x0)

          Aliases: NDerivative

          Attempt to calculate numerical derivative.

          See Wikipedia for more information.

   NumericalFourierSeriesCoefficients

NumericalFourierSeriesCoefficients (f,L,N)

          Return a vector of vectors [a,b] where a are the cosine
          coefficients and b are the sine coefficients of the
          Fourier series of f with half-period L (that is defined
          on [-L,L] and extended periodically) with coefficients
          up to Nth harmonic computed numerically. The
          coefficients are computed by numerical integration using
          NumericalIntegral.

          See Wikipedia or Mathworld for more information.

          Version 1.0.7 onwards.

   NumericalFourierSeriesFunction

NumericalFourierSeriesFunction (f,L,N)

          Return a function that is the Fourier series of f with
          half-period L (that is defined on [-L,L] and extended
          periodically) with coefficients up to Nth harmonic
          computed numerically. This is the trigonometric real
          series composed of sines and cosines. The coefficients
          are computed by numerical integration using
          NumericalIntegral.

          See Wikipedia or Mathworld for more information.

          Version 1.0.7 onwards.

   NumericalFourierCosineSeriesCoefficients

NumericalFourierCosineSeriesCoefficients (f,L,N)

          Return a vector of coefficients of the cosine Fourier
          series of f with half-period L. That is, we take f
          defined on [0,L] take the even periodic extension and
          compute the Fourier series, which only has cosine terms.
          The series is computed up to the Nth harmonic. The
          coefficients are computed by numerical integration using
          NumericalIntegral. Note that a@(1) is the constant
          coefficient! That is, a@(n) refers to the term
          cos(x*(n-1)*pi/L).

          See Wikipedia or Mathworld for more information.

          Version 1.0.7 onwards.

   NumericalFourierCosineSeriesFunction

NumericalFourierCosineSeriesFunction (f,L,N)

          Return a function that is the cosine Fourier series of f
          with half-period L. That is, we take f defined on [0,L]
          take the even periodic extension and compute the Fourier
          series, which only has cosine terms. The series is
          computed up to the Nth harmonic. The coefficients are
          computed by numerical integration using
          NumericalIntegral.

          See Wikipedia or Mathworld for more information.

          Version 1.0.7 onwards.

   NumericalFourierSineSeriesCoefficients

NumericalFourierSineSeriesCoefficients (f,L,N)

          Return a vector of coefficients of the sine Fourier
          series of f with half-period L. That is, we take f
          defined on [0,L] take the odd periodic extension and
          compute the Fourier series, which only has sine terms.
          The series is computed up to the Nth harmonic. The
          coefficients are computed by numerical integration using
          NumericalIntegral.

          See Wikipedia or Mathworld for more information.

          Version 1.0.7 onwards.

   NumericalFourierSineSeriesFunction

NumericalFourierSineSeriesFunction (f,L,N)

          Return a function that is the sine Fourier series of f
          with half-period L. That is, we take f defined on [0,L]
          take the odd periodic extension and compute the Fourier
          series, which only has sine terms. The series is
          computed up to the Nth harmonic. The coefficients are
          computed by numerical integration using
          NumericalIntegral.

          See Wikipedia or Mathworld for more information.

          Version 1.0.7 onwards.

   NumericalIntegral

NumericalIntegral (f,a,b)

          Integration by rule set in NumericalIntegralFunction of
          f from a to b using NumericalIntegralSteps steps.

   NumericalLeftDerivative

NumericalLeftDerivative (f,x0)

          Attempt to calculate numerical left derivative.

   NumericalLimitAtInfinity

NumericalLimitAtInfinity (_f,step_fun,tolerance,successive_for_success,N
)

          Attempt to calculate the limit of f(step_fun(i)) as i
          goes from 1 to N.

   NumericalRightDerivative

NumericalRightDerivative (f,x0)

          Attempt to calculate numerical right derivative.

   OddPeriodicExtension

OddPeriodicExtension (f,L)

          Return a function that is the odd periodic extension of
          f with half period L. That is a function defined on the
          interval [0,L] extended to be odd on [-L,L] and then
          extended to be periodic with period 2*L.

          See also EvenPeriodicExtension and PeriodicExtension.

          Version 1.0.7 onwards.

   OneSidedFivePointFormula

OneSidedFivePointFormula (f,x0,h)

          Compute one-sided derivative using five point formula.

   OneSidedThreePointFormula

OneSidedThreePointFormula (f,x0,h)

          Compute one-sided derivative using three-point formula.

   PeriodicExtension

PeriodicExtension (f,a,b)

          Return a function that is the periodic extension of f
          defined on the interval [a,b] and has period b-a.

          See also OddPeriodicExtension and EvenPeriodicExtension.

          Version 1.0.7 onwards.

   RightLimit

RightLimit (f,x0)

          Calculate the right limit of a real-valued function at
          x0.

   TwoSidedFivePointFormula

TwoSidedFivePointFormula (f,x0,h)

          Compute two-sided derivative using five-point formula.

   TwoSidedThreePointFormula

TwoSidedThreePointFormula (f,x0,h)

          Compute two-sided derivative using three-point formula.
     __________________________________________________________

11.12. Functions

   Argument

Argument (z)

          Aliases: Arg arg

          argument (angle) of complex number.

   BesselJ0

BesselJ0 (x)

          Bessel function of the first kind of order 0. Only
          implemented for real numbers.

          See Wikipedia for more information.

          Version 1.0.16 onwards.

   BesselJ1

BesselJ1 (x)

          Bessel function of the first kind of order 1. Only
          implemented for real numbers.

          See Wikipedia for more information.

          Version 1.0.16 onwards.

   BesselJn

BesselJn (n,x)

          Bessel function of the first kind of order n. Only
          implemented for real numbers.

          See Wikipedia for more information.

          Version 1.0.16 onwards.

   BesselY0

BesselY0 (x)

          Bessel function of the second kind of order 0. Only
          implemented for real numbers.

          See Wikipedia for more information.

          Version 1.0.16 onwards.

   BesselY1

BesselY1 (x)

          Bessel function of the second kind of order 1. Only
          implemented for real numbers.

          See Wikipedia for more information.

          Version 1.0.16 onwards.

   BesselYn

BesselYn (n,x)

          Bessel function of the second kind of order n. Only
          implemented for real numbers.

          See Wikipedia for more information.

          Version 1.0.16 onwards.

   DirichletKernel

DirichletKernel (n,t)

          Dirichlet kernel of order n.

   DiscreteDelta

DiscreteDelta (v)

          Returns 1 if and only if all elements are zero.

   ErrorFunction

ErrorFunction (x)

          Aliases: erf

          The error function, 2/sqrt(pi) * int_0^x e^(-t^2) dt.

          See Wikipedia or Planetmath for more information.

   FejerKernel

FejerKernel (n,t)

          Fejer kernel of order n evaluated at t

          See Planetmath for more information.

   GammaFunction

GammaFunction (x)

          Aliases: Gamma

          The Gamma function. Currently only implemented for real
          values.

          See Planetmath or Wikipedia for more information.

   KroneckerDelta

KroneckerDelta (v)

          Returns 1 if and only if all elements are equal.

   LambertW

LambertW (x)

          The principal branch of Lambert W function computed for
          only real values greater than or equal to -1/e. That is,
          LambertW is the inverse of the expression x*e^x. Even
          for real x this expression is not one to one and
          therefore has two branches over [-1/e,0). See LambertWm1
          for the other real branch.

          See Wikipedia for more information.

          Version 1.0.18 onwards.

   LambertWm1

LambertWm1 (x)

          The minus-one branch of Lambert W function computed for
          only real values greater than or equal to -1/e and less
          than 0. That is, LambertWm1 is the second branch of the
          inverse of x*e^x. See LambertW for the principal branch.

          See Wikipedia for more information.

   MinimizeFunction

MinimizeFunction (func,x,incr)

          Find the first value where f(x)=0.

   MoebiusDiskMapping

MoebiusDiskMapping (a,z)

          Moebius mapping of the disk to itself mapping a to 0.

          See Wikipedia or Planetmath for more information.

   MoebiusMapping

MoebiusMapping (z,z2,z3,z4)

          Moebius mapping using the cross ratio taking z2,z3,z4 to
          1,0, and infinity respectively.

          See Wikipedia or Planetmath for more information.

   MoebiusMappingInftyToInfty

MoebiusMappingInftyToInfty (z,z2,z3)

          Moebius mapping using the cross ratio taking infinity to
          infinity and z2,z3 to 1 and 0 respectively.

          See Wikipedia or Planetmath for more information.

   MoebiusMappingInftyToOne

MoebiusMappingInftyToOne (z,z3,z4)

          Moebius mapping using the cross ratio taking infinity to
          1 and z3,z4 to 0 and infinity respectively.

          See Wikipedia or Planetmath for more information.

   MoebiusMappingInftyToZero

MoebiusMappingInftyToZero (z,z2,z4)

          Moebius mapping using the cross ratio taking infinity to
          0 and z2,z4 to 1 and infinity respectively.

          See Wikipedia or Planetmath for more information.

   PoissonKernel

PoissonKernel (r,sigma)

          Poisson kernel on D(0,1) (not normalized to 1, that is
          integral of this is 2pi).

   PoissonKernelRadius

PoissonKernelRadius (r,sigma)

          Poisson kernel on D(0,R) (not normalized to 1).

   RiemannZeta

RiemannZeta (x)

          Aliases: zeta

          The Riemann zeta function. Currently only implemented
          for real values.

          See Planetmath or Wikipedia for more information.

   UnitStep

UnitStep (x)

          The unit step function is 0 for x<0, 1 otherwise. This
          is the integral of the Dirac Delta function. Also called
          the Heaviside function.

          See Wikipedia for more information.

   cis

cis (x)

          The cis function, that is the same as cos(x)+1i*sin(x)

   deg2rad

deg2rad (x)

          Convert degrees to radians.

   rad2deg

rad2deg (x)

          Convert radians to degrees.

   sinc

sinc (x)

          Calculates the unnormalized sinc function, that is
          sin(x)/x. If you want the normalized function call
          sinc(pi*x).

          See Wikipedia for more information.

          Version 1.0.16 onwards.
     __________________________________________________________

11.13. Equation Solving

   CubicFormula

CubicFormula (p)

          Compute roots of a cubic (degree 3) polynomial using the
          cubic formula. The polynomial should be given as a
          vector of coefficients. That is 4*x^3 + 2*x + 1
          corresponds to the vector [1,2,0,4]. Returns a column
          vector of the three solutions. The first solution is
          always the real one as a cubic always has one real
          solution.

          See Planetmath, Mathworld, or Wikipedia for more
          information.

   EulersMethod

EulersMethod (f,x0,y0,x1,n)

          Use classical Euler's method to numerically solve
          y'=f(x,y) for initial x0, y0 going to x1 with n
          increments, returns y at x1. Unless you explicitly want
          to use Euler's method, you should really think about
          using RungeKutta for solving ODE.

          Systems can be solved by just having y be a (column)
          vector everywhere. That is, y0 can be a vector in which
          case f should take a number x and a vector of the same
          size for the second argument and should return a vector
          of the same size.

          See Mathworld or Wikipedia for more information.

   EulersMethodFull

EulersMethodFull (f,x0,y0,x1,n)

          Use classical Euler's method to numerically solve
          y'=f(x,y) for initial x0, y0 going to x1 with n
          increments, returns an n+1 by 2 matrix with the x and y
          values. Unless you explicitly want to use Euler's
          method, you should really think about using
          RungeKuttaFull for solving ODE. Suitable for plugging
          into LinePlotDrawLine or LinePlotDrawPoints.

          Example:

genius> LinePlotClear();
genius> line = EulersMethodFull(`(x,y)=y,0,1.0,3.0,50);
genius> LinePlotDrawLine(line,"window","fit","color","blue","legend","Ex
ponential growth");

          Systems can be solved by just having y be a (column)
          vector everywhere. That is, y0 can be a vector in which
          case f should take a number x and a vector of the same
          size for the second argument and should return a vector
          of the same size.

          The output for a system is still a n by 2 matrix with
          the second entry being a vector. If you wish to plot the
          line, make sure to use row vectors, and then flatten the
          matrix with ExpandMatrix, and pick out the right
          columns. Example:

genius> LinePlotClear();
genius> lines = EulersMethodFull(`(x,y)=[y@(2),-y@(1)],0,[1.0,1.0],10.0,
500);
genius> lines = ExpandMatrix(lines);
genius> firstline = lines@(,[1,2]);
genius> secondline = lines@(,[1,3]);
genius> LinePlotWindow = [0,10,-2,2];
genius> LinePlotDrawLine(firstline,"color","blue","legend","First");
genius> LinePlotDrawPoints(secondline,"color","red","thickness",3,"legen
d","Second");

          See Mathworld or Wikipedia for more information.

          Version 1.0.10 onwards.

   FindRootBisection

FindRootBisection (f,a,b,TOL,N)

          Find root of a function using the bisection method. a
          and b are the initial guess interval, f(a) and f(b)
          should have opposite signs. TOL is the desired tolerance
          and N is the limit on the number of iterations to run, 0
          means no limit. The function returns a vector
          [success,value,iteration], where success is a boolean
          indicating success, value is the last value computed,
          and iteration is the number of iterations done.

   FindRootFalsePosition

FindRootFalsePosition (f,a,b,TOL,N)

          Find root of a function using the method of false
          position. a and b are the initial guess interval, f(a)
          and f(b) should have opposite signs. TOL is the desired
          tolerance and N is the limit on the number of iterations
          to run, 0 means no limit. The function returns a vector
          [success,value,iteration], where success is a boolean
          indicating success, value is the last value computed,
          and iteration is the number of iterations done.

   FindRootMullersMethod

FindRootMullersMethod (f,x0,x1,x2,TOL,N)

          Find root of a function using the Muller's method. TOL
          is the desired tolerance and N is the limit on the
          number of iterations to run, 0 means no limit. The
          function returns a vector [success,value,iteration],
          where success is a boolean indicating success, value is
          the last value computed, and iteration is the number of
          iterations done.

   FindRootSecant

FindRootSecant (f,a,b,TOL,N)

          Find root of a function using the secant method. a and b
          are the initial guess interval, f(a) and f(b) should
          have opposite signs. TOL is the desired tolerance and N
          is the limit on the number of iterations to run, 0 means
          no limit. The function returns a vector
          [success,value,iteration], where success is a boolean
          indicating success, value is the last value computed,
          and iteration is the number of iterations done.

   HalleysMethod

HalleysMethod (f,df,ddf,guess,epsilon,maxn)

          Find zeros using Halley's method. f is the function, df
          is the derivative of f, and ddf is the second derivative
          of f. guess is the initial guess. The function returns
          after two successive values are within epsilon of each
          other, or after maxn tries, in which case the function
          returns null indicating failure.

          See also NewtonsMethod and SymbolicDerivative.

          Example to find the square root of 10:

genius> HalleysMethod(`(x)=x^2-10,`(x)=2*x,`(x)=2,3,10^-10,100)

          See Wikipedia for more information.

          Version 1.0.18 onwards.

   NewtonsMethod

NewtonsMethod (f,df,guess,epsilon,maxn)

          Find zeros using Newton's method. f is the function and
          df is the derivative of f. guess is the initial guess.
          The function returns after two successive values are
          within epsilon of each other, or after maxn tries, in
          which case the function returns null indicating failure.

          See also NewtonsMethodPoly and SymbolicDerivative.

          Example to find the square root of 10:

genius> NewtonsMethod(`(x)=x^2-10,`(x)=2*x,3,10^-10,100)

          See Wikipedia for more information.

          Version 1.0.18 onwards.

   PolynomialRoots

PolynomialRoots (p)

          Compute roots of a polynomial (degrees 1 through 4)
          using one of the formulas for such polynomials. The
          polynomial should be given as a vector of coefficients.
          That is 4*x^3 + 2*x + 1 corresponds to the vector
          [1,2,0,4]. Returns a column vector of the solutions.

          The function calls QuadraticFormula, CubicFormula, and
          QuarticFormula.

   QuadraticFormula

QuadraticFormula (p)

          Compute roots of a quadratic (degree 2) polynomial using
          the quadratic formula. The polynomial should be given as
          a vector of coefficients. That is 3*x^2 + 2*x + 1
          corresponds to the vector [1,2,3]. Returns a column
          vector of the two solutions.

          See Planetmath, or Mathworld, or Wikipedia for more
          information.

   QuarticFormula

QuarticFormula (p)

          Compute roots of a quartic (degree 4) polynomial using
          the quartic formula. The polynomial should be given as a
          vector of coefficients. That is 5*x^4 + 2*x + 1
          corresponds to the vector [1,2,0,0,5]. Returns a column
          vector of the four solutions.

          See Planetmath, Mathworld, or Wikipedia for more
          information.

   RungeKutta

RungeKutta (f,x0,y0,x1,n)

          Use classical non-adaptive fourth order Runge-Kutta
          method to numerically solve y'=f(x,y) for initial x0, y0
          going to x1 with n increments, returns y at x1.

          Systems can be solved by just having y be a (column)
          vector everywhere. That is, y0 can be a vector in which
          case f should take a number x and a vector of the same
          size for the second argument and should return a vector
          of the same size.

          See Mathworld or Wikipedia for more information.

   RungeKuttaFull

RungeKuttaFull (f,x0,y0,x1,n)

          Use classical non-adaptive fourth order Runge-Kutta
          method to numerically solve y'=f(x,y) for initial x0, y0
          going to x1 with n increments, returns an n+1 by 2
          matrix with the x and y values. Suitable for plugging
          into LinePlotDrawLine or LinePlotDrawPoints.

          Example:

genius> LinePlotClear();
genius> line = RungeKuttaFull(`(x,y)=y,0,1.0,3.0,50);
genius> LinePlotDrawLine(line,"window","fit","color","blue","legend","Ex
ponential growth");

          Systems can be solved by just having y be a (column)
          vector everywhere. That is, y0 can be a vector in which
          case f should take a number x and a vector of the same
          size for the second argument and should return a vector
          of the same size.

          The output for a system is still a n by 2 matrix with
          the second entry being a vector. If you wish to plot the
          line, make sure to use row vectors, and then flatten the
          matrix with ExpandMatrix, and pick out the right
          columns. Example:

genius> LinePlotClear();
genius> lines = RungeKuttaFull(`(x,y)=[y@(2),-y@(1)],0,[1.0,1.0],10.0,10
0);
genius> lines = ExpandMatrix(lines);
genius> firstline = lines@(,[1,2]);
genius> secondline = lines@(,[1,3]);
genius> LinePlotWindow = [0,10,-2,2];
genius> LinePlotDrawLine(firstline,"color","blue","legend","First");
genius> LinePlotDrawPoints(secondline,"color","red","thickness",3,"legen
d","Second");

          See Mathworld or Wikipedia for more information.

          Version 1.0.10 onwards.
     __________________________________________________________

11.14. Statistics

   Average

Average (m)

          Aliases: average Mean mean

          Calculate average (the arithmetic mean) of an entire
          matrix.

          See Wikipedia or Mathworld for more information.

   GaussDistribution

GaussDistribution (x,sigma)

          Integral of the GaussFunction from 0 to x (area under
          the normal curve).

          See Wikipedia or Mathworld for more information.

   GaussFunction

GaussFunction (x,sigma)

          The normalized Gauss distribution function (the normal
          curve).

          See Wikipedia or Mathworld for more information.

   Median

Median (m)

          Aliases: median

          Calculate median of an entire matrix.

          See Wikipedia or Mathworld for more information.

   PopulationStandardDeviation

PopulationStandardDeviation (m)

          Aliases: stdevp

          Calculate the population standard deviation of a whole
          matrix.

   RowAverage

RowAverage (m)

          Aliases: RowMean

          Calculate average of each row in a matrix. That is,
          compute the arithmetic mean.

          See Wikipedia or Mathworld for more information.

   RowMedian

RowMedian (m)

          Calculate median of each row in a matrix and return a
          column vector of the medians.

          See Wikipedia or Mathworld for more information.

   RowPopulationStandardDeviation

RowPopulationStandardDeviation (m)

          Aliases: rowstdevp

          Calculate the population standard deviations of rows of
          a matrix and return a vertical vector.

   RowStandardDeviation

RowStandardDeviation (m)

          Aliases: rowstdev

          Calculate the standard deviations of rows of a matrix
          and return a vertical vector.

   StandardDeviation

StandardDeviation (m)

          Aliases: stdev

          Calculate the standard deviation of a whole matrix.
     __________________________________________________________

11.15. Polynomials

   AddPoly

AddPoly (p1,p2)

          Add two polynomials (vectors).

   DividePoly

DividePoly (p,q,&r)

          Divide two polynomials (as vectors) using long division.
          Returns the quotient of the two polynomials. The
          optional argument r is used to return the remainder. The
          remainder will have lower degree than q.

          See Planetmath for more information.

   IsPoly

IsPoly (p)

          Check if a vector is usable as a polynomial.

   MultiplyPoly

MultiplyPoly (p1,p2)

          Multiply two polynomials (as vectors).

   NewtonsMethodPoly

NewtonsMethodPoly (poly,guess,epsilon,maxn)

          Find a root of a polynomial using Newton's method. poly
          is the polynomial as a vector and guess is the initial
          guess. The function returns after two successive values
          are within epsilon of each other, or after maxn tries,
          in which case the function returns null indicating
          failure.

          See also NewtonsMethod.

          Example to find the square root of 10:

genius> NewtonsMethodPoly([-10,0,1],3,10^-10,100)

          See Wikipedia for more information.

   Poly2ndDerivative

Poly2ndDerivative (p)

          Take second polynomial (as vector) derivative.

   PolyDerivative

PolyDerivative (p)

          Take polynomial (as vector) derivative.

   PolyToFunction

PolyToFunction (p)

          Make function out of a polynomial (as vector).

   PolyToString

PolyToString (p,var...)

          Make string out of a polynomial (as vector).

   SubtractPoly

SubtractPoly (p1,p2)

          Subtract two polynomials (as vectors).

   TrimPoly

TrimPoly (p)

          Trim zeros from a polynomial (as vector).
     __________________________________________________________

11.16. Set Theory

   Intersection

Intersection (X,Y)

          Returns a set theoretic intersection of X and Y (X and Y
          are vectors pretending to be sets).

   IsIn

IsIn (x,X)

          Returns true if the element x is in the set X (where X
          is a vector pretending to be a set).

   IsSubset

IsSubset (X, Y)

          Returns true if X is a subset of Y (X and Y are vectors
          pretending to be sets).

   MakeSet

MakeSet (X)

          Returns a vector where every element of X appears only
          once.

   SetMinus

SetMinus (X,Y)

          Returns a set theoretic difference X-Y (X and Y are
          vectors pretending to be sets).

   Union

Union (X,Y)

          Returns a set theoretic union of X and Y (X and Y are
          vectors pretending to be sets).
     __________________________________________________________

11.17. Commutative Algebra

   MacaulayBound

MacaulayBound (c,d)

          For a Hilbert function that is c for degree d, given the
          Macaulay bound for the Hilbert function of degree d+1
          (The c^<d> operator from Green's proof).

          Version 1.0.15 onwards.

   MacaulayLowerOperator

MacaulayLowerOperator (c,d)

          The c_<d> operator from Green's proof of Macaulay's
          Theorem.

          Version 1.0.15 onwards.

   MacaulayRep

MacaulayRep (c,d)

          Return the dth Macaulay representation of a positive
          integer c.

          Version 1.0.15 onwards.
     __________________________________________________________

11.18. Miscellaneous

   ASCIIToString

ASCIIToString (vec)

          Convert a vector of ASCII values to a string. See also
          StringToASCII.

          Example:

genius> ASCIIToString([97,98,99])
= "abc"

          See Wikipedia for more information.

   AlphabetToString

AlphabetToString (vec,alphabet)

          Convert a vector of 0-based alphabet values (positions
          in the alphabet string) to a string. A null vector
          results in an empty string. See also StringToAlphabet.

          Examples:

genius> AlphabetToString([1,2,3,0,0],"abcd")
= "bcdaa"
genius> AlphabetToString(null,"abcd")
= ""

   StringToASCII

StringToASCII (str)

          Convert a string to a (row) vector of ASCII values. See
          also ASCIIToString.

          Example:

genius> StringToASCII("abc")
= [97, 98, 99]

          See Wikipedia for more information.

   StringToAlphabet

StringToAlphabet (str,alphabet)

          Convert a string to a (row) vector of 0-based alphabet
          values (positions in the alphabet string), -1's for
          unknown letters. An empty string results in a null. See
          also AlphabetToString.

          Examples:

genius> StringToAlphabet("cca","abcd")
= [2, 2, 0]
genius> StringToAlphabet("ccag","abcd")
= [2, 2, 0, -1]
     __________________________________________________________

11.19. Symbolic Operations

   SymbolicDerivative

SymbolicDerivative (f)

          Attempt to symbolically differentiate the function f,
          where f is a function of one variable.

          Examples:

genius> SymbolicDerivative(sin)
= (`(x)=cos(x))
genius> SymbolicDerivative(`(x)=7*x^2)
= (`(x)=(7*(2*x)))

          See Wikipedia for more information.

   SymbolicDerivativeTry

SymbolicDerivativeTry (f)

          Attempt to symbolically differentiate the function f,
          where f is a function of one variable, returns null if
          unsuccessful but is silent. (See SymbolicDerivative)

          See Wikipedia for more information.

   SymbolicNthDerivative

SymbolicNthDerivative (f,n)

          Attempt to symbolically differentiate a function n
          times. (See SymbolicDerivative)

          See Wikipedia for more information.

   SymbolicNthDerivativeTry

SymbolicNthDerivativeTry (f,n)

          Attempt to symbolically differentiate a function n times
          quietly and return null on failure (See
          SymbolicNthDerivative)

          See Wikipedia for more information.

   SymbolicTaylorApproximationFunction

SymbolicTaylorApproximationFunction (f,x0,n)

          Attempt to construct the Taylor approximation function
          around x0 to the nth degree. (See SymbolicDerivative)
     __________________________________________________________

11.20. Plotting

   ExportPlot

ExportPlot (file,type)

ExportPlot (file)

          Export the contents of the plotting window to a file.
          The type is a string that specifies the file type to
          use, "png", "eps", or "ps". If the type is not
          specified, then it is taken to be the extension, in
          which case the extension must be ".png", ".eps", or
          ".ps".

          Note that files are overwritten without asking.

          On successful export, true is returned. Otherwise error
          is printed and exception is raised.

          Examples:

genius> ExportPlot("file.png")
genius> ExportPlot("/directory/file","eps")

          Version 1.0.16 onwards.

   LinePlot

LinePlot (func1,func2,func3,...)

LinePlot (func1,func2,func3,x1,x2)

LinePlot (func1,func2,func3,x1,x2,y1,y2)

LinePlot (func1,func2,func3,[x1,x2])

LinePlot (func1,func2,func3,[x1,x2,y1,y2])

          Plot a function (or several functions) with a line.
          First (up to 10) arguments are functions, then
          optionally you can specify the limits of the plotting
          window as x1, x2, y1, y2. If limits are not specified,
          then the currently set limits apply (See LinePlotWindow)
          If the y limits are not specified, then the functions
          are computed and then the maxima and minima are used.

          The parameter LinePlotDrawLegends controls the drawing
          of the legend.

          Examples:

genius> LinePlot(sin,cos)
genius> LinePlot(`(x)=x^2,-1,1,0,1)

   LinePlotClear

LinePlotClear ()

          Show the line plot window and clear out functions and
          any other lines that were drawn.

   LinePlotCParametric

LinePlotCParametric (func,...)

LinePlotCParametric (func,t1,t2,tinc)

LinePlotCParametric (func,t1,t2,tinc,x1,x2,y1,y2)

          Plot a parametric complex valued function with a line.
          First comes the function that returns x+iy, then
          optionally the t limits as t1,t2,tinc, then optionally
          the limits as x1,x2,y1,y2.

          If limits are not specified, then the currently set
          limits apply (See LinePlotWindow). If instead the string
          "fit" is given for the x and y limits, then the limits
          are the maximum extent of the graph

          The parameter LinePlotDrawLegends controls the drawing
          of the legend.

   LinePlotDrawLine

LinePlotDrawLine (x1,y1,x2,y2,...)

LinePlotDrawLine (v,...)

          Draw a line from x1,y1 to x2,y2. x1,y1, x2,y2 can be
          replaced by an n by 2 matrix for a longer polyline.
          Alternatively the vector v may be a column vector of
          complex numbers, that is an n by 1 matrix and each
          complex number is then considered a point in the plane.

          Extra parameters can be added to specify line color,
          thickness, arrows, the plotting window, or legend. You
          can do this by adding an argument string "color",
          "thickness", "window", "arrow", or "legend", and after
          it specify the color, the thickness, the window as
          4-vector, type of arrow, or the legend. (Arrow and
          window are from version 1.0.6 onwards.)

          If the line is to be treated as a filled polygon, filled
          with the given color, you can specify the argument
          "filled". Since version 1.0.22 onwards.

          The color should be either a string indicating the
          common English word for the color that GTK will
          recognize such as "red", "blue", "yellow", etc...
          Alternatively the color can be specified in RGB format
          as "#rgb", "#rrggbb", or "#rrrrggggbbbb", where the r,
          g, or b are hex digits of the red, green, and blue
          components of the color. Finally, since version 1.0.18,
          the color can also be specified as a real vector
          specifying the red green and blue components where the
          components are between 0 and 1, e.g. [1.0,0.5,0.1].

          The window should be given as usual as [x1,x2,y1,y2], or
          alternatively can be given as a string "fit" in which
          case, the x range will be set precisely and the y range
          will be set with five percent borders around the line.

          Arrow specification should be "origin", "end", "both",
          or "none".

          Finally, legend should be a string that can be used as
          the legend in the graph. That is, if legends are being
          printed.

          Examples:

genius> LinePlotDrawLine(0,0,1,1,"color","blue","thickness",3)
genius> LinePlotDrawLine([0,0;1,-1;-1,-1])
genius> LinePlotDrawLine([0,0;1,1],"arrow","end")
genius> LinePlotDrawLine(RungeKuttaFull(`(x,y)=y,0,0.001,10,100),"color"
,"blue","legend","The Solution")
genius> for r=0.0 to 1.0 by 0.1 do LinePlotDrawLine([0,0;1,r],"color",[r
,(1-r),0.5],"window",[0,1,0,1])
genius> LinePlotDrawLine([0,0;10,0;10,10;0,10],"filled","color","green")

          Unlike many other functions that do not care if they
          take a column or a row vector, if specifying points as a
          vector of complex values, due to possible ambiguities,
          it must always be given as a column vector.

          Specifying v as a column vector of complex numbers is
          implemented from version 1.0.22 and onwards.

   LinePlotDrawPoints

LinePlotDrawPoints (x,y,...)

LinePlotDrawPoints (v,...)

          Draw a point at x,y. The input can be an n by 2 matrix
          for n different points. This function has essentially
          the same input as LinePlotDrawLine. Alternatively the
          vector v may be a column vector of complex numbers, that
          is an n by 1 matrix and each complex number is then
          considered a point in the plane.

          Extra parameters can be added to specify color,
          thickness, the plotting window, or legend. You can do
          this by adding an argument string "color", "thickness",
          "window", or "legend", and after it specify the color,
          the thickness, the window as 4-vector, or the legend.

          The color should be either a string indicating the
          common English word for the color that GTK will
          recognize such as "red", "blue", "yellow", etc...
          Alternatively the color can be specified in RGB format
          as "#rgb", "#rrggbb", or "#rrrrggggbbbb", where the r,
          g, or b are hex digits of the red, green, and blue
          components of the color. Finally the color can also be
          specified as a real vector specifying the red green and
          blue components where the components are between 0 and
          1.

          The window should be given as usual as [x1,x2,y1,y2], or
          alternatively can be given as a string "fit" in which
          case, the x range will be set precisely and the y range
          will be set with five percent borders around the line.

          Finally, legend should be a string that can be used as
          the legend in the graph. That is, if legends are being
          printed.

          Examples:

genius> LinePlotDrawPoints(0,0,"color","blue","thickness",3)
genius> LinePlotDrawPoints([0,0;1,-1;-1,-1])
genius> LinePlotDrawPoints(RungeKuttaFull(`(x,y)=y,0,0.001,10,100),"colo
r","blue","legend","The Solution")
genius> LinePlotDrawPoints([1;1+1i;1i;0],"thickness",5)
genius> LinePlotDrawPoints(ApplyOverMatrix((0:6)',`(k)=exp(k*2*pi*1i/7))
,"thickness",3,"legend","The 7th roots of unity")

          Unlike many other functions that do not care if they
          take a column or a row vector, if specifying points as a
          vector of complex values, due to possible ambiguities,
          it must always be given as a column vector. Therefore,
          notice in the last example the transpose of the vector
          0:6 to make it into a column vector.

          Available from version 1.0.18 onwards. Specifying v as a
          column vector of complex numbers is implemented from
          version 1.0.22 and onwards.

   LinePlotMouseLocation

LinePlotMouseLocation ()

          Returns a row vector of a point on the line plot
          corresponding to the current mouse location. If the line
          plot is not visible, then prints an error and returns
          null. In this case you should run LinePlot or
          LinePlotClear to put the graphing window into the line
          plot mode. See also LinePlotWaitForClick.

   LinePlotParametric

LinePlotParametric (xfunc,yfunc,...)

LinePlotParametric (xfunc,yfunc,t1,t2,tinc)

LinePlotParametric (xfunc,yfunc,t1,t2,tinc,x1,x2,y1,y2)

LinePlotParametric (xfunc,yfunc,t1,t2,tinc,[x1,x2,y1,y2])

LinePlotParametric (xfunc,yfunc,t1,t2,tinc,"fit")

          Plot a parametric function with a line. First come the
          functions for x and y then optionally the t limits as
          t1,t2,tinc, then optionally the limits as x1,x2,y1,y2.

          If x and y limits are not specified, then the currently
          set limits apply (See LinePlotWindow). If instead the
          string "fit" is given for the x and y limits, then the
          limits are the maximum extent of the graph

          The parameter LinePlotDrawLegends controls the drawing
          of the legend.

   LinePlotWaitForClick

LinePlotWaitForClick ()

          If in line plot mode, waits for a click on the line plot
          window and returns the location of the click as a row
          vector. If the window is closed the function returns
          immediately with null. If the window is not in line plot
          mode, it is put in it and shown if not shown. See also
          LinePlotMouseLocation.

   PlotCanvasFreeze

PlotCanvasFreeze ()

          Freeze drawing of the canvas plot temporarily. Useful if
          you need to draw a bunch of elements and want to delay
          drawing everything to avoid flicker in an animation.
          After everything has been drawn you should call
          PlotCanvasThaw.

          The canvas is always thawed after end of any execution,
          so it will never remain frozen. The moment a new command
          line is shown for example the plot canvas is thawed
          automatically. Also note that calls to freeze and thaw
          may be safely nested.

          Version 1.0.18 onwards.

   PlotCanvasThaw

PlotCanvasThaw ()

          Thaw the plot canvas frozen by PlotCanvasFreeze and
          redraw the canvas immediately. The canvas is also always
          thawed after end of execution of any program.

          Version 1.0.18 onwards.

   PlotWindowPresent

PlotWindowPresent ()

          Show and raise the plot window, creating it if
          necessary. Normally the window is created when one of
          the plotting functions is called, but it is not always
          raised if it happens to be below other windows. So this
          function is good to call in scripts where the plot
          window might have been created before, and by now is
          hidden behind the console or other windows.

          Version 1.0.19 onwards.

   SlopefieldClearSolutions

SlopefieldClearSolutions ()

          Clears the solutions drawn by the SlopefieldDrawSolution
          function.

   SlopefieldDrawSolution

SlopefieldDrawSolution (x, y, dx)

          When a slope field plot is active, draw a solution with
          the specified initial condition. The standard
          Runge-Kutta method is used with increment dx. Solutions
          stay on the graph until a different plot is shown or
          until you call SlopefieldClearSolutions. You can also
          use the graphical interface to draw solutions and
          specify initial conditions with the mouse.

   SlopefieldPlot

SlopefieldPlot (func)

SlopefieldPlot (func,x1,x2,y1,y2)

          Plot a slope field. The function func should take two
          real numbers x and y, or a single complex number.
          Optionally you can specify the limits of the plotting
          window as x1, x2, y1, y2. If limits are not specified,
          then the currently set limits apply (See
          LinePlotWindow).

          The parameter LinePlotDrawLegends controls the drawing
          of the legend.

          Examples:

genius> SlopefieldPlot(`(x,y)=sin(x-y),-5,5,-5,5)

   SurfacePlot

SurfacePlot (func)

SurfacePlot (func,x1,x2,y1,y2,z1,z2)

SurfacePlot (func,x1,x2,y1,y2)

SurfacePlot (func,[x1,x2,y1,y2,z1,z2])

SurfacePlot (func,[x1,x2,y1,y2])

          Plot a surface function that takes either two arguments
          or a complex number. First comes the function then
          optionally limits as x1, x2, y1, y2, z1, z2. If limits
          are not specified, then the currently set limits apply
          (See SurfacePlotWindow). Genius can only plot a single
          surface function at this time.

          If the z limits are not specified then the maxima and
          minima of the function are used.

          Examples:

genius> SurfacePlot(|sin|,-1,1,-1,1,0,1.5)
genius> SurfacePlot(`(x,y)=x^2+y,-1,1,-1,1,-2,2)
genius> SurfacePlot(`(z)=|z|^2,-1,1,-1,1,0,2)

   SurfacePlotClear

SurfacePlotClear ()

          Show the surface plot window and clear out functions and
          any other lines that were drawn.

          Available in version 1.0.19 and onwards.

   SurfacePlotData

SurfacePlotData (data)

SurfacePlotData (data,label)

SurfacePlotData (data,x1,x2,y1,y2,z1,z2)

SurfacePlotData (data,label,x1,x2,y1,y2,z1,z2)

SurfacePlotData (data,[x1,x2,y1,y2,z1,z2])

SurfacePlotData (data,label,[x1,x2,y1,y2,z1,z2])

          Plot a surface from data. The data is an n by 3 matrix
          whose rows are the x, y and z coordinates. The data can
          also be simply a vector whose length is a multiple of 3
          and so contains the triples of x, y, z. The data should
          contain at least 3 points.

          Optionally we can give the label and also optionally the
          limits. If limits are not given, they are computed from
          the data, SurfacePlotWindow is not used, if you want to
          use it, pass it in explicitly. If label is not given
          then empty label is used.

          Examples:

genius> SurfacePlotData([0,0,0;1,0,1;0,1,1;1,1,3])
genius> SurfacePlotData(data,"My data")
genius> SurfacePlotData(data,-1,1,-1,1,0,10)
genius> SurfacePlotData(data,SurfacePlotWindow)

          Here's an example of how to plot in polar coordinates,
          in particular how to plot the function -r^2 * theta:

genius> d:=null; for r=0 to 1 by 0.1 do for theta=0 to 2*pi by pi/5 do d
=[d;[r*cos(theta),r*sin(theta),-r^2*theta]];
genius> SurfacePlotData(d)

          Version 1.0.16 onwards.

   SurfacePlotDataGrid

SurfacePlotDataGrid (data,[x1,x2,y1,y2])

SurfacePlotDataGrid (data,[x1,x2,y1,y2,z1,z2])

SurfacePlotDataGrid (data,[x1,x2,y1,y2],label)

SurfacePlotDataGrid (data,[x1,x2,y1,y2,z1,z2],label)

          Plot a surface from regular rectangular data. The data
          is given in a n by m matrix where the rows are the x
          coordinate and the columns are the y coordinate. The x
          coordinate is divided into equal n-1 subintervals and y
          coordinate is divided into equal m-1 subintervals. The
          limits x1 and x2 give the interval on the x-axis that we
          use, and the limits y1 and y2 give the interval on the
          y-axis that we use. If the limits z1 and z2 are not
          given they are computed from the data (to be the extreme
          values from the data).

          Optionally we can give the label, if label is not given
          then empty label is used.

          Examples:

genius> SurfacePlotDataGrid([1,2;3,4],[0,1,0,1])
genius> SurfacePlotDataGrid(data,[-1,1,-1,1],"My data")
genius> d:=null; for i=1 to 20 do for j=1 to 10 do d@(i,j) = (0.1*i-1)^2
-(0.1*j)^2;
genius> SurfacePlotDataGrid(d,[-1,1,0,1],"half a saddle")

          Version 1.0.16 onwards.

   SurfacePlotDrawLine

SurfacePlotDrawLine (x1,y1,z1,x2,y2,z2,...)

SurfacePlotDrawLine (v,...)

          Draw a line from x1,y1,z1 to x2,y2,z2. x1,y1,z1,
          x2,y2,z2 can be replaced by an n by 3 matrix for a
          longer polyline.

          Extra parameters can be added to specify line color,
          thickness, the plotting window, or legend. You can do
          this by adding an argument string "color", "thickness",
          "window", or "legend", and after it specify the color,
          the thickness, the window as 6-vector, or the legend.

          The color should be either a string indicating the
          common English word for the color that GTK will
          recognize such as "red", "blue", "yellow", etc...
          Alternatively the color can be specified in RGB format
          as "#rgb", "#rrggbb", or "#rrrrggggbbbb", where the r,
          g, or b are hex digits of the red, green, and blue
          components of the color. Finally, since version 1.0.18,
          the color can also be specified as a real vector
          specifying the red green and blue components where the
          components are between 0 and 1, e.g. [1.0,0.5,0.1].

          The window should be given as usual as
          [x1,x2,y1,y2,z1,z2], or alternatively can be given as a
          string "fit" in which case, the x range will be set
          precisely and the y range will be set with five percent
          borders around the line.

          Finally, legend should be a string that can be used as
          the legend in the graph. That is, if legends are being
          printed.

          Examples:

genius> SurfacePlotDrawLine(0,0,0,1,1,1,"color","blue","thickness",3)
genius> SurfacePlotDrawLine([0,0,0;1,-1,2;-1,-1,-3])

          Available from version 1.0.19 onwards.

   SurfacePlotDrawPoints

SurfacePlotDrawPoints (x,y,z,...)

SurfacePlotDrawPoints (v,...)

          Draw a point at x,y,z. The input can be an n by 3 matrix
          for n different points. This function has essentially
          the same input as SurfacePlotDrawLine.

          Extra parameters can be added to specify line color,
          thickness, the plotting window, or legend. You can do
          this by adding an argument string "color", "thickness",
          "window", or "legend", and after it specify the color,
          the thickness, the window as 6-vector, or the legend.

          The color should be either a string indicating the
          common English word for the color that GTK will
          recognize such as "red", "blue", "yellow", etc...
          Alternatively the color can be specified in RGB format
          as "#rgb", "#rrggbb", or "#rrrrggggbbbb", where the r,
          g, or b are hex digits of the red, green, and blue
          components of the color. Finally the color can also be
          specified as a real vector specifying the red green and
          blue components where the components are between 0 and
          1.

          The window should be given as usual as
          [x1,x2,y1,y2,z1,z2], or alternatively can be given as a
          string "fit" in which case, the x range will be set
          precisely and the y range will be set with five percent
          borders around the line.

          Finally, legend should be a string that can be used as
          the legend in the graph. That is, if legends are being
          printed.

          Examples:

genius> SurfacePlotDrawPoints(0,0,0,"color","blue","thickness",3)
genius> SurfacePlotDrawPoints([0,0,0;1,-1,2;-1,-1,1])

          Available from version 1.0.19 onwards.

   VectorfieldClearSolutions

VectorfieldClearSolutions ()

          Clears the solutions drawn by the
          VectorfieldDrawSolution function.

          Version 1.0.6 onwards.

   VectorfieldDrawSolution

VectorfieldDrawSolution (x, y, dt, tlen)

          When a vector field plot is active, draw a solution with
          the specified initial condition. The standard
          Runge-Kutta method is used with increment dt for an
          interval of length tlen. Solutions stay on the graph
          until a different plot is shown or until you call
          VectorfieldClearSolutions. You can also use the
          graphical interface to draw solutions and specify
          initial conditions with the mouse.

          Version 1.0.6 onwards.

   VectorfieldPlot

VectorfieldPlot (funcx, funcy)

VectorfieldPlot (funcx, funcy, x1, x2, y1, y2)

          Plot a two dimensional vector field. The function funcx
          should be the dx/dt of the vectorfield and the function
          funcy should be the dy/dt of the vectorfield. The
          functions should take two real numbers x and y, or a
          single complex number. When the parameter
          VectorfieldNormalized is true, then the magnitude of the
          vectors is normalized. That is, only the direction and
          not the magnitude is shown.

          Optionally you can specify the limits of the plotting
          window as x1, x2, y1, y2. If limits are not specified,
          then the currently set limits apply (See
          LinePlotWindow).

          The parameter LinePlotDrawLegends controls the drawing
          of the legend.

          Examples:

genius> VectorfieldPlot(`(x,y)=x^2-y, `(x,y)=y^2-x, -1, 1, -1, 1)
     __________________________________________________________

Chapter 12. Example Programs in GEL

   Here is a function that calculates factorials:
function f(x) = if x <= 1 then 1 else (f(x-1)*x)

   With indentation it becomes:
function f(x) = (
  if x <= 1 then
    1
  else
    (f(x-1)*x)
)

   This is a direct port of the factorial function from the bc
   manpage. The syntax seems similar to bc, but different in that
   in GEL, the last expression is the one that is returned. Using
   the return function instead, it would be:
function f(x) = (
  if (x <= 1) then return (1);
  return (f(x-1) * x)
)

   By far the easiest way to define a factorial function would be
   using the product loop as follows. This is not only the
   shortest and fastest, but also probably the most readable
   version.
function f(x) = prod k=1 to x do k

   Here is a larger example, this basically redefines the internal
   ref function to calculate the row echelon form of a matrix. The
   function ref is built in and much faster, but this example
   demonstrates some of the more complex features of GEL.
# Calculate the row-echelon form of a matrix
function MyOwnREF(m) = (
  if not IsMatrix(m) or not IsValueOnly(m) then
    (error("MyOwnREF: argument not a value only matrix");bailout);
  s := min(rows(m), columns(m));
  i := 1;
  d := 1;
  while d <= s and i <= columns(m) do (

    # This just makes the anchor element non-zero if at
    # all possible
    if m@(d,i) == 0 then (
      j := d+1;
      while j <= rows(m) do (
        if m@(j,i) == 0 then
          (j=j+1;continue);
        a := m@(j,);
        m@(j,) := m@(d,);
        m@(d,) := a;
        j := j+1;
        break
      )
    );
    if m@(d,i) == 0 then
      (i:=i+1;continue);

    # Here comes the actual zeroing of all but the anchor
    # element rows
    j := d+1;
    while j <= rows(m)) do (
      if m@(j,i) != 0 then (
        m@(j,) := m@(j,)-(m@(j,i)/m@(d,i))*m@(d,)
      );
      j := j+1
    );
    m@(d,) := m@(d,) * (1/m@(d,i));
    d := d+1;
    i := i+1
  );
  m
)
     __________________________________________________________

Chapter 13. Settings

   To configure Genius Mathematics Tool, choose
   Settings->Preferences. There are several basic parameters
   provided by the calculator in addition to the ones provided by
   the standard library. These control how the calculator behaves.

   Note Changing Settings with GEL


   Many of the settings in Genius are simply global variables, and
   can be evaluated and assigned to in the same way as normal
   variables. See Section 5.2 about evaluating and assigning to
   variables, and Section 11.3 for a list of settings that can be
   modified in this way.

   As an example, you can set the maximum number of digits in a
   result to 12 by typing:
MaxDigits = 12
     __________________________________________________________

13.1. Output

   Maximum digits to output
          The maximum digits in a result (MaxDigits)

   Results as floats
          If the results should be always printed as floats
          (ResultsAsFloats)

   Floats in scientific notation
          If floats should be in scientific notation
          (ScientificNotation)

   Always print full expressions
          Should we print out full expressions for non-numeric
          return values (longer than a line) (FullExpressions)

   Use mixed fractions
          If fractions should be printed as mixed fractions such
          as "1 1/3" rather than "4/3". (MixedFractions)

   Display 0.0 when floating point number is less than 10^-x
          (0=never chop)
          How to chop output. But only when other numbers nearby
          are large. See the documentation of the parameter
          OutputChopExponent.

   Only chop numbers when another number is greater than 10^-x
          When to chop output. This is set by the parameter
          OutputChopWhenExponent. See the documentation of the
          parameter OutputChopExponent.

   Remember output settings across sessions
          Should the output settings in the Number/Expression
          output options frame be remembered for next session.
          Does not apply to the Error/Info output options frame.

          If unchecked, either the default or any previously saved
          settings are used each time Genius starts up. Note that
          settings are saved at the end of the session, so if you
          wish to change the defaults check this box, restart
          Genius Mathematics Tool and then uncheck it again.

   Display errors in a dialog
          If set the errors will be displayed in a separate
          dialog, if unset the errors will be printed on the
          console.

   Display information messages in a dialog
          If set the information messages will be displayed in a
          separate dialog, if unset the information messages will
          be printed on the console.

   Maximum errors to display
          The maximum number of errors to return on one evaluation
          (MaxErrors). If you set this to 0 then all errors are
          always returned. Usually if some loop causes many
          errors, then it is unlikely that you will be able to
          make sense out of more than a few of these, so seeing a
          long list of errors is usually not helpful.

   In addition to these preferences, there are some preferences
   that can only be changed by setting them in the workspace
   console. For others that may affect the output see Section
   11.3.

   IntegerOutputBase
          The base that will be used to output integers

   OutputStyle
          A string, can be "normal", "latex", "mathml" or "troff"
          and it will affect how matrices (and perhaps other
          stuff) is printed, useful for pasting into documents.
          Normal style is the default human readable printing
          style of Genius Mathematics Tool. The other styles are
          for typesetting in LaTeX, MathML (XML), or in Troff.
     __________________________________________________________

13.2. Precision

   Floating point precision
          The floating point precision in bits (FloatPrecision).
          Note that changing this only affects newly computed
          quantities. Old values stored in variables are obviously
          still in the old precision and if you want to have them
          more precise you will have to recompute them. Exceptions
          to this are the system constants such as pi or e.

   Remember precision setting across sessions
          Should the precision setting be remembered for the next
          session. If unchecked, either the default or any
          previously saved setting is used each time Genius starts
          up. Note that settings are saved at the end of the
          session, so if you wish to change the default check this
          box, restart genius and then uncheck it again.
     __________________________________________________________

13.3. Terminal

   Terminal refers to the console in the work area.

   Scrollback lines
          Lines of scrollback in the terminal.

   Font
          The font to use on the terminal.

   Black on white
          If to use black on white on the terminal.

   Blinking cursor
          If the cursor in the terminal should blink when the
          terminal is in focus. This can sometimes be annoying and
          it generates idle traffic if you are using Genius
          remotely.
     __________________________________________________________

13.4. Memory

   Maximum number of nodes to allocate
          Internally all data is put onto small nodes in memory.
          This gives a limit on the maximum number of nodes to
          allocate for computations. This limit avoids the problem
          of running out of memory if you do something by mistake
          that uses too much memory, such as a recursion without
          end. This could slow your computer and make it hard to
          even interrupt the program.

          Once the limit is reached, Genius Mathematics Tool asks
          if you wish to interrupt the computation or if you wish
          to continue. If you continue, no limit is applied and it
          will be possible to run your computer out of memory. The
          limit will be applied again next time you execute a
          program or an expression on the Console regardless of
          how you answered the question.

          Setting the limit to zero means there is no limit to the
          amount of memory that genius uses.
     __________________________________________________________

Chapter 14. About Genius Mathematics Tool

   Genius Mathematics Tool was written by Jiř (George) Lebl
   (<jirka@5z.com>). The history of Genius Mathematics Tool goes
   back to late 1997. It was the first calculator program for
   GNOME, but it then grew beyond being just a desktop calculator.
   To find more information about Genius Mathematics Tool, please
   visit the Genius Web page.

   To report a bug or make a suggestion regarding this application
   or this manual, send email to me (the author) or post to the
   mailing list (see the web page).

   This program is distributed under the terms of the GNU General
   Public license as published by the Free Software Foundation;
   either version 3 of the License, or (at your option) any later
   version. A copy of this license can be found at this link, or
   in the file COPYING included with the source code of this
   program.

   Jiř Lebl was during various parts of the development partially
   supported for the work by NSF grants DMS 0900885, DMS 1362337,
   the University of Illinois at Urbana-Champaign, the University
   of California at San Diego, the University of
   Wisconsin-Madison, and Oklahoma State University. The software
   has been used for both teaching and research.