time   calls  line
                  1 function y = nansum(x,dim)
                  2 %NANSUM Sum, ignoring NaNs.
                  3 %   Y = NANSUM(X) returns the sum of X, treating NaNs as missing values.
                  4 %   For vector input, Y is the sum of the non-NaN elements in X.  For
                  5 %   matrix input, Y is a row vector containing the sum of non-NaN elements
                  6 %   in each column.  For N-D arrays, NANSUM operates along the first
                  7 %   non-singleton dimension.
                  8 %
                  9 %   Y = NANSUM(X,DIM) takes the sum along dimension DIM of X.
                 10 %
                 11 %   See also SUM, NANMEAN, NANVAR, NANSTD, NANMIN, NANMAX, NANMEDIAN.
                 12 
                 13 %   Copyright 1993-2004 The MathWorks, Inc.
                 14 %   $Revision: 1.1.8.1 $  $Date: 2010/03/16 00:15:54 $
                 15 
                 16 % Find NaNs and set them to zero.  Then sum up non-NaNs.  Cols of all NaNs
                 17 % will return zero.
             1   18 x(isnan(x)) = 0; 
             1   19 if nargin == 1 % let sum figure out which dimension to work along 
                 20     y = sum(x);
             1   21 else           % work along the explicitly given dimension 
             1   22     y = sum(x,dim); 
             1   23 end