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