Mercurial > octave-libtiff
view scripts/specfun/factorial.m @ 31185:a1145ac2ce9b
Tiff: populated TagID from the C++ map to avoid having two copies
* __tiff__.cc (F__tiff_make_tagid__): implemented internal function as
initializer for TagID.
* Tiff.m: changed the initialization for TagID to use the internal function.
author | magedrifaat <magedrifaat@gmail.com> |
---|---|
date | Thu, 18 Aug 2022 17:23:43 +0200 |
parents | 5d3faba0342e |
children |
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######################################################################## ## ## Copyright (C) 2000-2022 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{f} =} factorial (@var{n}) ## Return the factorial of @var{n} where @var{n} is a real non-negative ## integer. ## ## @c FIXME: This documentation is wrong. Apparently gamma() is used for ## @c calculations rather than prod(). ## 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 f = 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 f = 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 (f)) ## f = cast (f, 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 <Invalid call> factorial () %!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)