X-Git-Url: https://git.creatis.insa-lyon.fr/pubgit/?p=CreaPhase.git;a=blobdiff_plain;f=octave_packages%2Fm%2Fspecfun%2Fbeta.m;fp=octave_packages%2Fm%2Fspecfun%2Fbeta.m;h=e8c7548b7439b2a7ffab97e1935873a53292f690;hp=0000000000000000000000000000000000000000;hb=1c0469ada9531828709108a4882a751d2816994a;hpb=63de9f36673d49121015e3695f2c336ea92bc278
diff --git a/octave_packages/m/specfun/beta.m b/octave_packages/m/specfun/beta.m
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+## Copyright (C) 1994-2012 John W. Eaton
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING. If not, see
+## .
+
+## -*- texinfo -*-
+## @deftypefn {Mapping Function} {} beta (@var{a}, @var{b})
+## For real inputs, return the Beta function,
+## @tex
+## $$
+## B (a, b) = {\Gamma (a) \Gamma (b) \over \Gamma (a + b)}.
+## $$
+## @end tex
+## @ifnottex
+##
+## @example
+## beta (a, b) = gamma (a) * gamma (b) / gamma (a + b).
+## @end example
+##
+## @end ifnottex
+## @end deftypefn
+
+## Author: KH
+## Created: 13 June 1993
+## Adapted-By: jwe
+
+function retval = beta (a, b)
+
+ if (nargin != 2)
+ print_usage ();
+ endif
+
+ if (any (size (a) != size (b)) && numel (a) != 1 && numel (b) != 1)
+ error ("beta: inputs A and B have inconsistent sizes");
+ endif
+
+ if (! isreal (a) || ! isreal (b))
+ error ("beta: inputs A and B must be real");
+ endif
+
+ retval = real (exp (gammaln (a) + gammaln (b) - gammaln (a+b)));
+
+endfunction
+
+%!test
+%! a=[1, 1.5, 2, 3];
+%! b=[4, 3, 2, 1];
+%! v1=beta(a,b);
+%! v2=beta(b,a);
+%! v3=gamma(a).*gamma(b)./gamma(a+b);
+%! assert(all(abs(v1-v2)