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annotate scripts/specfun/factorial.m @ 17441:2973de961a66

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stairs.m: Overhaul function. * scripts/plot/stairs.m: Clean up indentation. Fix input validation for size mismatch and linestyle arguments. Correctly implement color rotation for multiple columns. Accept linestyle argument to change line and marker properties. Add titles to %!demos. Add %!error tests for input validation.
author Rik <rik@octave.org>
date Wed, 18 Sep 2013 13:01:48 -0700
parents f3d52523cde1
children
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72c96de7a403 maint: update copyright notices for 2012
John W. Eaton <jwe@octave.org>
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1 ## Copyright (C) 2000-2012 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(:) != fix (n(:))))
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33 error ("factorial: N must all be non-negative 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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39 %!assert (factorial (5), prod (1:5))
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40 %!assert (factorial ([1,2;3,4]), [1,2;6,24])
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41 %!assert (factorial (70), exp (sum (log (1:70))), -128*eps)
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43 %!fail ("factorial (5.5)", "must all be non-negative integers")
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44 %!fail ("factorial (-3)", "must all be non-negative integers")
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