Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nan-2.5.5 / normpdf.m

diff --git a/octave_packages/nan-2.5.5/normpdf.m b/octave_packages/nan-2.5.5/normpdf.m
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+++ b/octave_packages/nan-2.5.5/normpdf.m
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+function p = normpdf(x,m,s)
+% NORMPDF returns normal probability density 
+%
+% pdf = normpdf(x,m,s);
+%
+% Computes the PDF of a the normal distribution 
+%    with mean m and standard deviation s
+%    default: m=0; s=1;
+% x,m,s must be matrices of same size, or any one can be a scalar. 
+%
+% see also: NORMCDF, NORMINV 
+
+% Reference(s):
+
+%    $Id: normpdf.m 9033 2011-11-08 20:58:07Z schloegl $
+%    Copyright (C) 2000-2003,2010,2011 by Alois Schloegl <alois.schloegl@gmail.com>    
+%    This function is part of the NaN-toolbox
+%    http://pub.ist.ac.at/~schloegl/matlab/NaN/
+
+%    This program 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 2 of the License, or
+%    (at your option) any later version.
+%
+%    This program 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 this program; If not, see <http://www.gnu.org/licenses/>.
+
+if nargin==1,
+        m=0;s=1;
+elseif nargin==2,
+        s=1;
+end;        
+
+% allocate output memory and check size of argument
+z = (x-m)./s;          % if this line causes an error, input arguments do not fit. 
+
+%p = ((2*pi)^(-1/2))*exp(-z.^2/2)./s;
+SQ2PI = 2.5066282746310005024157652848110;
+p = exp(-z.^2/2)./(s*SQ2PI);
+
+p((x==m) & (s==0)) = inf;
+
+p(isinf(z)~=0) = 0;
+
+p(isnan(x) | isnan(m) | isnan(s) | (s<0)) = nan;
+
+%!assert(sum(isnan(normpdf([-inf,-2,-1,-.5,0,.5,1,2,3,inf,nan]',2,0))),1)
+
+