Logo Search packages:      
Sourcecode: octave-nan version File versions  Download package

normpdf.m

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):

%     $Revision: 4585 $
%     $Id: normpdf.m 4585 2008-02-04 13:47:45Z adb014 $
%     Version 1.28   Date: 13 Mar 2003
%     Copyright (C) 2000-2003 by Alois Schloegl <a.schloegl@ieee.org>   

%    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;


Generated by  Doxygen 1.6.0   Back to index