function [o,count,SSQ,S4M] = sumskipnan(i,DIM)% SUMSKIPNAN adds all non-NaN values. %% All NaN's are skipped; NaN's are considered as missing values. % SUMSKIPNAN of NaN's only  gives O; and the number of valid elements is return. % SUMSKIPNAN is also the elementary function for calculating % various statistics (e.g. MEAN, STD, VAR, RMS, MEANSQ, SKEWNESS, % KURTOSIS, MOMENT, STATISTIC etc.) from data with missing values.  % SUMSKIPNAN implements the DIMENSION-argument for data with missing values.% Also the second output argument return the number of valid elements (not NaNs) % % Y = sumskipnan(x [,DIM])% [Y,N,SSQ] = sumskipnan(x [,DIM])% % DIM	dimension%	1 sum of columns%	2 sum of rows%	default or []: first DIMENSION with more than 1 element%% Y	resulting sum% N	number of valid (not missing) elements% SSQ	sum of squares%% The mean & standard error of the mean and %	Y./N & sqrt((SSQ-Y.*Y./N)./(N.*max(N-1,0))); % the mean square & the standard error of the mean square and% 	SSQ./N & sqrt((S4M-SSQ.^2./N)./(N.*max(N-1,0)))%% features:% - can deal with NaN's (missing values)% - implements dimension argument. % - compatible with Matlab and Octave%% see also: SUM, NANSUM, MEAN, STD, VAR, RMS, MEANSQ, %      SSQ, MOMENT, SKEWNESS, KURTOSIS, SEM%    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, write to the Free Software%    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA%	$Revision: 1.23 $%	$Id: sumskipnan.m,v 1.23 2003/10/31 18:15:38 schloegl Exp $%    Copyright (C) 2000-2003 by Alois Schloegl <a.schloegl@ieee.org>	
if nargin<2,
        DIM = [];
end;
% an efficient implementation in C of the following lines % could significantly increase performance % only one loop and only one check for isnan is needed.
% A MEX-Implementation is available in sumskipnan.cpp.%% Outline of the algorithm: % for { k=1,o=0,count=0; k++; k<N} % 	if ~isnan(i(k)) % 	{ 	o     += i(k);%               count += 1;%		tmp    = i(k)*i(k)%		o2    += tmp;%		o3    += tmp.*tmp;%       }; 

if isempty(DIM),        DIM=min(find(size(i)>1));        if isempty(DIM), DIM = 1; end;end;if nargout>1,        count = sum(~isnan(i),DIM); end;
%if flag_implicit_skip_nan, %%% skip always NaN'si(isnan(i)) = 0;%end;
o = sum(i,DIM);if nargout>2,        i = real(i).^2 + imag(i).^2;        SSQ = sum(i,DIM);        if nargout>3,                S4M = sum(i.^2,DIM);        end;
end;