Mercurial > octave-nkf
view scripts/specfun/factorial.m @ 20584:eb9e2d187ed2
maint: Use Octave coding conventions in scripts/ode/private dir.
* AbsRel_Norm.m, fuzzy_compare.m, hermite_quartic_interpolation.m,
integrate_adaptive.m, integrate_const.m, integrate_n_steps.m, kahan.m,
ode_struct_value_check.m, odepkg_event_handle.m, odepkg_structure_check.m,
runge_kutta_45_dorpri.m, starting_stepsize.m:
Wrap long lines to < 80 chars.
Use double quotes rather than single quotes where possible.
Use ';' at end of keywords "return;" and "break;"
Use '##" for stand-alone comments and '#' for end-of-line comments.
Use two spaces after period before starting new sentence.
Use '!' instead of '~' for logical negation.
Use specific form of end (endif, endfor, etc.).
Don't use line continuation marker '...' unless necessary.
author | Rik <rik@octave.org> |
---|---|
date | Sun, 04 Oct 2015 22:18:54 -0700 |
parents | 4197fc428c7d |
children |
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## Copyright (C) 2000-2015 Paul Kienzle ## ## This file is part of Octave. ## ## Octave 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. ## ## Octave 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 Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {} factorial (@var{n}) ## Return the factorial of @var{n} where @var{n} is a real non-negative integer. ## ## If @var{n} is a scalar, this is equivalent to @code{prod (1:@var{n})}. For ## vector or matrix arguments, return the factorial of each element in the ## array. ## ## For non-integers see the generalized factorial function @code{gamma}. ## Note that the factorial function grows large quite quickly, and even ## with double precision values overflow will occur if @var{n} > 171. For ## such cases consider @code{gammaln}. ## @seealso{prod, gamma, gammaln} ## @end deftypefn function x = factorial (n) if (nargin != 1) print_usage (); elseif (! isreal (n) || any (n(:) < 0 | n(:) != fix (n(:)))) error ("factorial: all N must be real non-negative integers"); endif x = round (gamma (n+1)); ## FIXME: Matlab returns an output of the same type as the input. ## This doesn't seem particularly worth copying--for example uint8 would ## saturate for n > 5. If desired, however, the following code could be ## uncommented. # if (! isfloat (x)) # x = cast (x, class (n)); # endif endfunction %!assert (factorial (5), prod (1:5)) %!assert (factorial ([1,2;3,4]), [1,2;6,24]) %!assert (factorial (70), exp (sum (log (1:70))), -128*eps) %!assert (factorial (0), 1) %!error factorial () %!error factorial (1,2) %!error <must be real non-negative integers> factorial (2i) %!error <must be real non-negative integers> factorial (-3) %!error <must be real non-negative integers> factorial (5.5)