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## Copyright (C) 2014 Carnë Draug <carandraug@octave.org>
##
## This program is free software; you can redistribute it and/or modify it
## 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.
##
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; see the file COPYING. If not, see
## <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {} unitsratio (@var{to}, @var{from})
## Return ratio for conversion between units.
##
## Returns the conversion ratio between two units, @var{to} and @var{from}, so
## that:
##
## @group
## @example
## unitsratio ("meter", "centimeter")
## @result{ratio } 100
##
## unitsratio ("inch", "foot")
## @result{ratio } 12
## @end example
## @end group
##
## This allows for easy conversion between units, for example:
##
## @group
## @example
## unitsratio ("mile", "km") * 156
## @result{156 km in miles }96.93391
## @end example
## @end group
##
## For conversion between angle units, @qcode{"degrees"} and
## @qcode{"radians"} are supported. For conversion between length units,
## supports units defined in @code{validateLengthUnit}.
##
## @seealso{units, validateLengthUnit}
## @end deftypefn
## Author: Carnë Draug <carandraug@octave.org>
function ratio = unitsratio (to, from)
if (nargin != 2)
print_usage ();
endif
try
valid_to = validatestring (to, {"radians", "degrees"});
valid_from = validatestring (from, {"radians", "degrees"});
catch
valid_to = validateLengthUnit (to, "unitsratio", "TO");
valid_from = validateLengthUnit (from, "unitsratio", "FROM");
end_try_catch
persistent ratios = struct (
## angle units
"degrees", struct (
"degrees", 1,
"radians", pi / 180
),
"radians", struct (
"degrees", 180 / pi,
"radians", 1
),
## length units
"meter", struct (
"meter", 1,
"centimeter", 100,
"millimeter", 1000,
"micron", 10^6,
"kilometer", 0.001,
"nautical mile", 1 / 1852,
"foot", 1 / 0.3048,
"inch", 1 / 0.0254,
"yard", 1 / 0.9144,
"mile", 1 / 1609.344,
"U.S. survey foot", 3937 / 1200,
"U.S. survey mile (statute mile)", 3937 / (1200 * 5280), # 5280 survey foot
"Clarke's foot", 1 / 0.3047972654,
"German legal metre", 1 / 1.0000135965,
"Indian foot", 1 / 0.3047996
),
## same as meter times 0.01
"centimeter", struct (
"meter", 0.01,
"centimeter", 0.01 * 100,
"millimeter", 0.01 * 1000,
"micron", 0.01 * 10^6,
"kilometer", 0.01 * 0.001,
"nautical mile", 0.01 / 1852,
"foot", 0.01 / 0.3048,
"inch", 0.01 / 0.0254,
"yard", 0.01 / 0.9144,
"mile", 0.01 / 1609.344,
"U.S. survey foot", 0.01 * (3937 / 1200),
"U.S. survey mile (statute mile)", 0.01 * 3937 / (1200 * 5280),
"Clarke's foot", 0.01 / 0.3047972654,
"German legal metre", 0.01 / 1.0000135965,
"Indian foot", 0.01 / 0.3047996
),
## same as meter times 0.001
"millimeter", struct (
"meter", 0.001,
"centimeter", 0.001 * 100,
"millimeter", 0.001 * 1000,
"micron", 0.001 * 10^6,
"kilometer", 0.001 * 0.001,
"nautical mile", 0.001 / 1852,
"foot", 0.001 / 0.3048,
"inch", 0.001 / 0.0254,
"yard", 0.001 / 0.9144,
"mile", 0.001 / 1609.344,
"U.S. survey foot", 0.001 * (3937 / 1200),
"U.S. survey mile (statute mile)", 0.001 * 3937 / (1200 * 5280),
"Clarke's foot", 0.001 / 0.3047972654,
"German legal metre", 0.001 / 1.0000135965,
"Indian foot", 0.001 / 0.3047996
),
## same as meter times 10^-6
"micron", struct (
"meter", 10^-6,
"centimeter", 10^-6 * 100,
"millimeter", 10^-6 * 1000,
"micron", 10^-6 * 10^6,
"kilometer", 10^-6 * 0.001,
"nautical mile", 10^-6 / 1852,
"foot", 10^-6 / 0.3048,
"inch", 10^-6 / 0.0254,
"yard", 10^-6 / 0.9144,
"mile", 10^-6 / 1609.344,
"U.S. survey foot", 10^-6 * (3937 / 1200),
"U.S. survey mile (statute mile)", 10^-6 * 3937 / (1200 * 5280),
"Clarke's foot", 10^-6 / 0.3047972654,
"German legal metre", 10^-6 / 1.0000135965,
"Indian foot", 10^-6 / 0.3047996
),
## same as meter times 1000
"kilometer", struct (
"meter", 1000,
"centimeter", 1000 * 100,
"millimeter", 1000 * 1000,
"micron", 1000 * 1000000,
"kilometer", 1000 * 0.001,
"nautical mile", 1000 / 1852,
"foot", 1000 / 0.3048,
"inch", 1000 / 0.0254,
"yard", 1000 / 0.9144,
"mile", 1000 / 1609.344,
"U.S. survey foot", 1000 * (3937 / 1200),
"U.S. survey mile (statute mile)", 1000 * 3937 / (1200 * 5280),
"Clarke's foot", 1000 / 0.3047972654,
"German legal metre", 1000 / 1.0000135965,
"Indian foot", 1000 / 0.3047996
),
## exactly 1852 meters
"nautical mile", struct (
"meter", 1852,
"centimeter", 1852 * 100,
"millimeter", 1852 * 1000,
"micron", 1852 * 10^6,
"kilometer", 1852 * 0.001,
"nautical mile", 1,
"foot", 2315000 / 381, # thank you wikipedia
"inch", 27780000 / 381,
"yard", 2315000 / 1143, # thank you wikipedia
"mile", 1852 / 1609.344, # from how many meters are in a mile
"U.S. survey foot", 1852 * 3937 / 1200, # from how many meters are in US survey foot
"U.S. survey mile (statute mile)", 57875 / 50292,
"Clarke's foot", 1852 / 0.3047972654,
"German legal metre", 1852 / 1.0000135965,
"Indian foot", 1852 / 0.3047996 # from how many meters are in an indian foot
),
## exactly 0.3048 meters. Also 12 inch
"foot", struct (
"meter", 0.3048,
"centimeter", 0.3048 * 100,
"millimeter", 0.3048 * 1000,
"micron", 0.3048 * 10^6,
"kilometer", 0.3048 * 0.001,
"nautical mile", 381 / 2315000, # inverse from nautical mile to foot
"foot", 1,
"inch", 12,
"yard", 1 / 3,
"mile", 1 / 5280,
"U.S. survey foot", 0.3048 / (1200 / 3937),
"U.S. survey mile (statute mile)", (5280 * 3977) / (0.3048 * 1200),
"Clarke's foot", 0.3048 / 0.3047972654,
"German legal metre", 0.3048 / 1.0000135965,
"Indian foot", 0.3048 / 0.3047996
),
## exactly 0.0254 meters
"inch", struct (
"meter", 0.0254,
"centimeter", 0.0254 * 100,
"millimeter", 0.0254 * 1000,
"micron", 0.0254 * 10^6,
"kilometer", 0.0254 * 0.001,
"nautical mile", 381 / 27780000, # inverse from nautical mile to inch
"foot", 1 / 12,
"inch", 1,
"yard", 1 / 36,
"mile", 1 / (5280 * 12),
"U.S. survey foot", 0.0254 / (1200 / 3937),
"U.S. survey mile (statute mile)", (5280 * 3977) / (0.0254 * 1200),
"Clarke's foot", 0.0254 / 0.3047972654,
"German legal metre", 0.0254 / 1.0000135965,
"Indian foot", 0.0254 / 0.3047996
),
## exactly 0.9144 meters. Also 3 feet
"yard", struct (
"meter", 0.9144,
"centimeter", 0.9144 * 100,
"millimeter", 0.9144 * 1000,
"micron", 0.9144 * 10^6,
"kilometer", 0.9144 * 0.001,
"nautical mile", 1143 / 2315000, # inverse from nautical mile to yard
"foot", 3,
"inch", 36,
"yard", 1,
"mile", 3 / 5280,
"U.S. survey foot", 0.9144 / (1200 / 3937),
"U.S. survey mile (statute mile)", (5280 * 3977) / (0.9144 * 1200),
"Clarke's foot", 0.9144 / 0.3047972654,
"German legal metre", 0.9144 / 1.0000135965,
"Indian foot", 0.9144 / 0.3047996
),
## exactly 1609.344 meters. Also 5280 feet
"mile", struct (
"meter", 1609.344,
"centimeter", 1609.344 * 100,
"millimeter", 1609.344 * 1000,
"micron", 1609.344 * 10^6,
"kilometer", 1609.344 * 0.001,
"nautical mile", 1609.344 / 1852,
"foot", 5280,
"inch", 5280 * 12,
"yard", 5280 / 3,
"mile", 1,
"U.S. survey foot", 1609.344 / (1200 / 3937),
"U.S. survey mile (statute mile)", (5280 * 3977) / (1609.344 * 1200),
"Clarke's foot", 1609.344 / 0.3047972654,
"German legal metre", 1609.344 / 1.0000135965,
"Indian foot", 1609.344 / 0.3047996
),
## exactly 1200 / 3937
"U.S. survey foot", struct (
"meter", 1200 / 3937,
"centimeter", 100 * 1200 / 3937,
"millimeter", 1000 * 1200 / 3937,
"micron", 10^6 * 1200 / 3937,
"kilometer", 0.001 * 1200 / 3937,
"nautical mile", 1200 / (1852 * 3937),
"foot", (1200 / 3937) / 0.3048,
"inch", (1200 / 3937) / 0.0254,
"yard", (1200 / 3937) / 0.9144,
"mile", (1200 / 3937) / 1609.344,
"U.S. survey foot", 1,
"U.S. survey mile (statute mile)", 1 / 5280,
"Clarke's foot", 1200 / (0.3047972654 * 3937),
"German legal metre", 1200 / (1.0000135965 * 3937),
"Indian foot", 1200 / (0.3047996 * 3937)
),
## the U.S. survey mile is 5280 survey feet (survey foot = 1200 / 3937 meters)
"U.S. survey mile (statute mile)", struct (
"meter", 5280 * 1200 / 3937,
"centimeter", 100 * 5280 * 1200 / 3937,
"millimeter", 1000 * 5280 * 1200 / 3937,
"micron", 10^6 * 5280 * 1200 / 3937,
"kilometer", 0.001 * 5280 * 1200 / 3937,
"nautical mile", 50292 / 57875,
"foot", (0.3048 * 1200) / (5280 * 3977),
"inch", (0.0254 * 1200) / (5280 * 3977),
"yard", (0.9144 * 1200) / (5280 * 3977),
"mile", (1609.344 * 1200) / (5280 * 3977),
"U.S. survey foot", 5280,
"U.S. survey mile (statute mile)", 1,
"Clarke's foot", (5280 * 1200) / (0.3047972654 * 3937),
"German legal metre", (5280 * 1200) / (1.0000135965 * 3937),
"Indian foot", (5280 * 1200) / (0.3047996 * 3937)
),
## Defined as 0.3047972654 meters (from georepository.com)
"Clarke's foot", struct (
"meter", 0.3047972654,
"centimeter", 0.3047972654 * 100,
"millimeter", 0.3047972654 * 1000,
"micron", 0.3047972654 * 10^6,
"kilometer", 0.3047972654 * 0.001,
"nautical mile", 0.3047972654 / 1852,
"foot", 0.3047972654 / 0.3048,
"inch", 0.3047972654 / 0.0254,
"yard", 0.3047972654 / 0.9144,
"mile", 0.3047972654 / 1609.344,
"U.S. survey foot", (0.3047972654 * 3937) / 1200,
"U.S. survey mile (statute mile)", (0.3047972654 * 3937) / (5280 * 1200),
"Clarke's foot", 1,
"German legal metre", 0.3047972654 / 1.0000135965,
"Indian foot", 0.3047972654 / 0.3047996
),
## Defined as 1.0000135965 meters (longer than a meter by 13.5965 micrometers)
"German legal metre", struct (
"meter", 1.0000135965,
"centimeter", 1.0000135965 * 100,
"millimeter", 1.0000135965 * 1000,
"micron", 1.0000135965 * 10^6,
"kilometer", 1.0000135965 * 0.001,
"nautical mile", 1.0000135965 / 1852,
"foot", 1.0000135965 / 0.3048,
"inch", 1.0000135965 / 0.0254,
"yard", 1.0000135965 / 0.9144,
"mile", 1.0000135965 / 1609.344,
"U.S. survey foot", (1.0000135965 * 3937) / 1200,
"U.S. survey mile (statute mile)", (1.0000135965 * 3937) / (5280 * 1200),
"Clarke's foot", 1.0000135965 / 0.3047972654,
"German legal metre", 1,
"Indian foot", 1.0000135965 / 0.3047996
),
## The Indian survey foot is defined as exactly 0.3047996 m (wikipedia)
"Indian foot", struct (
"meter", 0.3047996,
"centimeter", 0.3047996 * 100,
"millimeter", 0.3047996 * 1000,
"micron", 0.3047996 * 10^6,
"kilometer", 0.3047996 * 0.001,
"nautical mile", 0.3047996 / 1852,
"foot", 0.3047996 / 0.3048,
"inch", 0.3047996 / 0.0254,
"yard", 0.3047996 / 0.9144,
"mile", 0.3047996 / 1609.344,
"U.S. survey foot", (0.3047996 * 3937) / 1200,
"U.S. survey mile (statute mile)", (0.3047996 * 3937) / (5280 * 1200),
"Clarke's foot", 0.3047996 / 0.3047972654,
"German legal metre", 0.3047996 / 1.0000135965,
"Indian foot", 1
)
);
try
ratio = ratios.(valid_from).(valid_to);
catch
error ("unitsratio: unknown conversion from %s to %s", from, to);
end_try_catch
endfunction
%!assert (unitsratio ("inch", "foot"), 12)
%!assert (unitsratio ("m", "cm"), 0.01)
%!assert (unitsratio ("cm", "m"), 100)
%!assert (unitsratio ("meter", "meter"), 1)
%!assert (unitsratio ("degrees", "radians"), 180 / pi)
%!assert (unitsratio ("radians", "degrees"), pi / 180)
%!error <unknown unit> unitsratio ("NOT A UNIT", "meter")
%!error <unknown unit> unitsratio ("meter", "NOT A UNIT")
|
