--- /dev/null
+function [o,count,SSQ] = sumskipnan(x, DIM, W)
+% 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])
+% [...] = sumskipnan(x, DIM, W)
+%
+% x input data
+% DIM dimension (default: [])
+% empty DIM sets DIM to first non singleton dimension
+% W weight vector for weighted sum, numel(W) must fit size(x,DIM)
+% Y resulting sum
+% N number of valid (not missing) elements
+% SSQ sum of squares
+%
+% the function FLAG_NANS_OCCURED() returns whether any value in x
+% is a not-a-number (NaN)
+%
+% features:
+% - can deal with NaN's (missing values)
+% - implements dimension argument.
+% - computes weighted sum
+% - compatible with Matlab and Octave
+%
+% see also: FLAG_NANS_OCCURED, 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 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/>.
+
+% $Id: sumskipnan.m 9033 2011-11-08 20:58:07Z schloegl $
+% Copyright (C) 2000-2005,2009,2011 by Alois Schloegl <alois.schloegl@gmail.com>
+% This function is part of the NaN-toolbox
+% http://pub.ist.ac.at/~schloegl/matlab/NaN/
+
+
+global FLAG_NANS_OCCURED;
+
+if nargin<2,
+ DIM = [];
+end;
+if nargin<3,
+ W = [];
+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
+% An 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 += x(k);
+% count += 1;
+% tmp = x(k)*x(k)
+% o2 += tmp;
+% o3 += tmp.*tmp;
+% };
+
+if isempty(DIM),
+ DIM = find(size(x)>1,1);
+ if isempty(DIM), DIM = 1; end;
+end
+if (DIM<1), DIM = 1; end; %% Hack, because min([])=0 for FreeMat v3.5
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% non-float data
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+if (isempty(W) && (~(isa(x,'float') || isa(x,'double')))) || ~flag_implicit_skip_nan(), %%% skip always NaN's
+ if ~isempty(W)
+ error('SUMSKIPNAN: weighted sum of integers not supported, yet');
+ end;
+ x = double(x);
+ o = sum(x,DIM);
+ if nargout>1
+ sz = size(x);
+ N = sz(DIM);
+ sz(DIM) = 1;
+ count = repmat(N,sz);
+ if nargout>2
+ x = x.*x;
+ SSQ = sum(x,DIM);
+ end;
+ end;
+ return;
+end;
+
+if (length(size(x))<DIM)
+ error('SUMSKIPNAN: DIM argument larger than number of dimensions of x');
+elseif ~isempty(W) && (size(x,DIM)~=numel(W))
+ error('SUMSKIPNAN: size of weight vector does not match size(x,DIM)');
+end;
+
+%% mex and oct files expect double
+x = double(x);
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% use Matlab-MEX function when available
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%if 1,
+try
+
+ %% using sumskipnan_mex.mex
+
+ %% !!! hack: FLAG_NANS_OCCURED is an output argument, reserve memory !!!
+ if isempty(FLAG_NANS_OCCURED),
+ FLAG_NANS_OCCURED = logical(0); % default value
+ end;
+
+ if (nargout<2),
+ o = sumskipnan_mex(real(x),DIM,FLAG_NANS_OCCURED,W);
+ if (~isreal(x))
+ io = sumskipnan_mex(imag(x),DIM,FLAG_NANS_OCCURED,W);
+ o = o + i*io;
+ end;
+ return;
+ elseif (nargout==2),
+ [o,count] = sumskipnan_mex(real(x),DIM,FLAG_NANS_OCCURED,W);
+ if (~isreal(x))
+ [io,icount] = sumskipnan_mex(imag(x),DIM,FLAG_NANS_OCCURED,W);
+ if any(count(:)-icount(:))
+ error('Number of NaNs differ for REAL and IMAG part');
+ else
+ o = o+i*io;
+ end;
+ end;
+ return;
+ elseif (nargout>=3),
+ [o,count,SSQ] = sumskipnan_mex(real(x),DIM,FLAG_NANS_OCCURED,W);
+ if (~isreal(x))
+ [io,icount,iSSQ] = sumskipnan_mex(imag(x),DIM,FLAG_NANS_OCCURED,W);
+ if any(count(:)-icount(:))
+ error('Number of NaNs differ for REAL and IMAG part');
+ else
+ o = o+i*io;
+ SSQ = SSQ+iSSQ;
+ end;
+ end;
+ return;
+ end;
+end;
+
+if ~isempty(W)
+ error('weighted sumskipnan requires sumskipnan_mex');
+end;
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% count non-NaN's
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+if nargout>1,
+ count = sum(x==x,DIM);
+ FLAG_NANS_OCCURED = any(count(:)<size(x,DIM));
+end;
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% replace NaN's with zero
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+x(x~=x) = 0;
+o = sum(x,DIM);
+
+if nargout>2,
+ x = real(x).^2 + imag(x).^2;
+ SSQ = sum(x,DIM);
+end;
+
+%!assert(sumskipnan([1,2],1),[1,2])
+%!assert(sumskipnan([1,NaN],2),1)
+%!assert(sumskipnan([1,NaN],2),1)
+%!assert(sumskipnan([nan,1,4,5]),10)
+%!assert(sumskipnan([nan,1,4,5]',1,[3;2;1;0]),6)
+
+
+
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