|
5820
|
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 |
|
5963
|
34 n (n < 1) = 1; |
|
5820
|
35 m = max (n(:)); |
|
|
36 c = cumprod (1:m); |
|
|
37 x = c(floor (n)); |
|
|
38 endif |
|
|
39 endfunction |
