Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/nan-2.5.5/sem.m b/octave_packages/nan-2.5.5/sem.m
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+++ b/octave_packages/nan-2.5.5/sem.m
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+function [SE,M]=sem(x,DIM, W)
+% SEM calculates the standard error of the mean
+% 
+% [SE,M] = SEM(x [, DIM [,W]])
+%   calculates the standard error (SE) in dimension DIM
+%   the default DIM is the first non-single dimension
+%   M returns the mean. 
+%   Can deal with complex data, too. 
+%
+% DIM  dimension
+%      1: SEM of columns
+%      2: SEM of rows
+%      N: SEM of  N-th dimension 
+%      default or []: first DIMENSION, with more than 1 element
+% W    weights to compute weighted mean and s.d. (default: [])
+%      if W=[], all weights are 1. 
+%      number of elements in W must match size(x,DIM) 
+%
+% features:
+% - can deal with NaN's (missing values)
+% - weighting of data 
+% - dimension argument 
+% - compatible to Matlab and Octave
+%
+% see also: SUMSKIPNAN, MEAN, VAR, STD
+
+%    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 3 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/>.
+
+%      Copyright (C) 2000-2003,2008,2009 by Alois Schloegl <alois.schloegl@gmail.com>  
+%      $Id: sem.m 8223 2011-04-20 09:16:06Z schloegl $
+%       This function is part of the NaN-toolbox
+%       http://pub.ist.ac.at/~schloegl/matlab/NaN/
+
+
+if nargin>2,
+       [S,N,SSQ] = sumskipnan(x,DIM,W);
+elseif nargin>1,
+       [S,N,SSQ] = sumskipnan(x,DIM);
+else    
+       [S,N,SSQ] = sumskipnan(x);
+end
+
+M  = S./N;
+SE = (SSQ.*N - real(S).^2 - imag(S).^2)./(N.*N.*(N-1)); 
+SE(SE<=0) = 0;         % prevent negative value caused by round-off error  
+SE = sqrt(real(SE));
+