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<refentry id="GEN20">
<indexterm id="IndexGEN20"><primary>GEN20</primary></indexterm>
<refmeta>
<refentrytitle>GEN20</refentrytitle>
</refmeta>
<refnamediv>
<refname>GEN20</refname>
<refpurpose>
Generates functions of different windows.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
This subroutine generates functions of different windows. These windows are usually used for spectrum analysis or for grain envelopes.
</para>
</refsect1>
<refsect1>
<title>Syntax</title>
<synopsis><command>f</command> # time size 20 window max [opt]</synopsis>
</refsect1>
<refsect1>
<title>Initialization</title>
<para>
<emphasis>size</emphasis> -- number of points in the table. Must be a power of 2 ( + 1).
</para>
<para>
<emphasis>window</emphasis> -- Type of window to generate:
<itemizedlist>
<listitem>
<para>1 = Hamming</para>
</listitem>
<listitem>
<para>2 = Hanning</para>
</listitem>
<listitem>
<para>3 = Bartlett ( triangle)</para>
</listitem>
<listitem>
<para>4 = Blackman ( 3-term)</para>
</listitem>
<listitem>
<para>5 = Blackman - Harris ( 4-term)</para>
</listitem>
<listitem>
<para>6 = Gaussian</para>
</listitem>
<listitem>
<para>7 = Kaiser</para>
</listitem>
<listitem>
<para>8 = Rectangle</para>
</listitem>
<listitem>
<para>9 = Sync</para>
</listitem>
</itemizedlist>
</para>
<para>
<emphasis>max</emphasis> -- For negative p4 this will be the absolute
value at window peak point. If p4 is positive or p4 is negative
and p6 is missing the table will be post-rescaled to a maximum
value of 1.
</para>
<para>
<emphasis>opt</emphasis> -- Optional argument required by the
Gaussian window and the Kaiser window.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
<informalexample>
<programlisting>
<emphasis role="stamnt">f</emphasis> 1 0 1024 20 5</programlisting>
</informalexample>
This creates a function which contains a 4 - term Blackman - Harris window with maximum value of 1.
</para>
<para>
<informalexample>
<programlisting>
<emphasis role="stamnt">f</emphasis> 1 0 1024 -20 2 456</programlisting>
</informalexample>
This creates a function that contains a Hanning window with a maximum value of 456.
</para>
<para>
<informalexample>
<programlisting>
<emphasis role="stamnt">f</emphasis> 1 0 1024 -20 1</programlisting>
</informalexample>
This creates a function that contains a Hamming window with a maximum value of 1.
</para>
<para>
<informalexample>
<programlisting>
<emphasis role="stamnt">f</emphasis> 1 0 1024 20 7 1 2</programlisting>
</informalexample>
This creates a function that contains a Kaiser window with a maximum value of 1. The extra argument specifies how "open" the window is, for example a value of 0 results in a rectangular window and a value of 10 in a Hamming like window.
</para>
<para>
<informalexample>
<programlisting>
<emphasis role="stamnt">f</emphasis> 1 0 1024 20 6 1 2</programlisting>
</informalexample>
This creates a function that contains a Gaussian window with a
maximum value of 1. The extra argument specifies how broad the
window is, as the standard deviation of the curve; in this
example the s.d. is 2. The default value is 1.
</para>
<para>
For all diagrams, see <link linkend="MiscWindows"><citetitle>Window Functions</citetitle></link>
</para>
<para>
Here is an example of the GEN20 routine. It uses the file <ulink url="examples/gen20.csd"><citetitle>gen20.csd</citetitle></ulink>.
<example>
<title>Example of the GEN20 routine.</title>
<para>See the sections <link linkend="UsingRealTime"><citetitle>Real-time Audio</citetitle></link> and <link linkend="CommandFlags"><citetitle>Command Line Flags</citetitle></link> for more information on using command line flags.</para>
<xi:include href="examples-xml/gen20.csd.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
</example>
<textobject>
<phrase>These are the diagrams of the waveforms of the GEN20 routines, as used in the example:</phrase>
</textobject>
<mediaobject>
<imageobject>
<imagedata fileref="images/gen20_1.png" format="PNG"/>
</imageobject>
<textobject>
<phrase> f 1 0 512 20 2 - Hanning window</phrase>
</textobject>
<caption>
<para> f 1 0 512 20 2 - Hanning window</para>
</caption>
</mediaobject>
<mediaobject>
<imageobject>
<imagedata fileref="images/gen20_2.png" format="PNG"/>
</imageobject>
<textobject>
<phrase> f 2 0 512 20 6 1 - Gaussian window</phrase>
</textobject>
<caption>
<para> f 2 0 512 20 6 1 - Gaussian window</para>
</caption>
</mediaobject>
</para>
</refsect1>
<refsect1>
<title>Credits</title>
<para>
<simplelist>
<member>Author: &nameparis;</member>
<member>MIT, Cambridge</member>
<member>1995</member>
</simplelist>
</para>
<para>
<simplelist>
<member>Author: &namejohn;</member>
<member>University of Bath/Codemist Ltd.</member>
<member>Bath, UK</member>
</simplelist>
</para>
<para>New in Csound version 3.2</para>
<para>Optional argument to Gaussian added in 5.10</para>
</refsect1>
</refentry>
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