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annotate scripts/specfun/factorial.m @ 12541:dd2c70b30f28

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Add tests for ifftshift.m
author Robert T. Short <octave@phaselockedsystems.com.com>
date Sat, 26 Mar 2011 06:50:12 -0700
parents fd0a3ac60b0e
children 984359717d71
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fd0a3ac60b0e update copyright notices
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1 ## Copyright (C) 2000-2011 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 3 of the License, or (at
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8 ## your option) 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, see
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17 ## <http://www.gnu.org/licenses/>.
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} factorial (@var{n})
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21 ## Return the factorial of @var{n} where @var{n} is a positive integer. If
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22 ## @var{n} is a scalar, this is equivalent to @code{prod (1:@var{n})}. For
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23 ## vector or matrix arguments, return the factorial of each element in the
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24 ## array. For non-integers see the generalized factorial function
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25 ## @code{gamma}.
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26 ## @seealso{prod, gamma}
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27 ## @end deftypefn
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29 function x = factorial (n)
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30 if (nargin != 1)
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31 print_usage ();
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32 elseif (any (n(:) < 0 | n(:) != round (n(:))))
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33 error ("factorial: N must all be nonnegative integers");
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34 endif
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35 x = round (gamma (n+1));
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36 endfunction
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37
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38 %!assert (factorial(5), prod(1:5))
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39 %!assert (factorial([1,2;3,4]), [1,2;6,24])
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40 %!assert (factorial(70), exp(sum(log(1:70))), -128*eps)
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41 %!fail ('factorial(5.5)', "must all be nonnegative integers")
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42 %!fail ('factorial(-3)', "must all be nonnegative integers")