Mercurial > octave-nkf
comparison scripts/specfun/factorial.m @ 5820:27c966e4b2dc
[project @ 2006-05-17 21:00:54 by jwe]
| author | jwe |
|---|---|
| date | Wed, 17 May 2006 21:00:54 +0000 |
| parents | |
| children | b3478d7a0486 |
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| 5819:e54c11df0524 | 5820:27c966e4b2dc |
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| 1 ## Copyright (C) 2000 Paul Kienzle | |
| 2 ## | |
| 3 ## This file is part of Octave. | |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6 ## under the terms of the GNU General Public License as published by | |
| 7 ## the Free Software Foundation; either version 2, or (at your option) | |
| 8 ## any later version. | |
| 9 ## | |
| 10 ## Octave is distributed in the hope that it will be useful, but | |
| 11 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 ## General Public License for more details. | |
| 14 ## | |
| 15 ## You should have received a copy of the GNU General Public License | |
| 16 ## along with Octave; see the file COPYING. If not, write to the Free | |
| 17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
| 18 ## 02110-1301, USA. | |
| 19 | |
| 20 ## -*- texinfo -*- | |
| 21 ## @deftypefn {Function File} {} factorial (@var{n}) | |
| 22 ## Return the factorial of @var{n}. If @var{n} is scalar, this is | |
| 23 ## equivalent to @code{prod (1:@var{n})}. If @var{n} is an array, | |
| 24 ## the factorial of the elements of the array are returned. | |
| 25 ## @end deftypefn | |
| 26 | |
| 27 function x = factorial (n) | |
| 28 if (any (n(:) < 0)) | |
| 29 error ("factorial: n be be a scalar or array of positive integers"); | |
| 30 endif | |
| 31 if (isscalar (n)) | |
| 32 x = prod (2:n); | |
| 33 else | |
| 34 n (find (n < 1)) = 1; | |
| 35 m = max (n(:)); | |
| 36 c = cumprod (1:m); | |
| 37 x = c(floor (n)); | |
| 38 endif | |
| 39 endfunction |