time   calls  line
                  1 function y = mean(x,dim)
                  2 %MEAN   Average or mean value.
                  3 %   For vectors, MEAN(X) is the mean value of the elements in X. For
                  4 %   matrices, MEAN(X) is a row vector containing the mean value of
                  5 %   each column.  For N-D arrays, MEAN(X) is the mean value of the
                  6 %   elements along the first non-singleton dimension of X.
                  7 %
                  8 %   MEAN(X,DIM) takes the mean along the dimension DIM of X. 
                  9 %
                 10 %   Example: If X = [1 2 3; 3 3 6; 4 6 8; 4 7 7];
                 11 %
                 12 %   then mean(X,1) is [3.0000 4.5000 6.0000] and 
                 13 %   mean(X,2) is [2.0000 4.0000 6.0000 6.0000].'
                 14 %
                 15 %   Class support for input X:
                 16 %      float: double, single
                 17 %
                 18 %   See also MEDIAN, STD, MIN, MAX, VAR, COV, MODE.
                 19 
                 20 %   Copyright 1984-2009 The MathWorks, Inc. 
                 21 %   $Revision: 5.17.4.5 $  $Date: 2010/09/02 13:35:22 $
                 22 
          1272   23 if nargin==1,  
                 24   % Determine which dimension SUM will use
  0.02    1063   25   dim = find(size(x)~=1, 1 ); 
          1063   26   if isempty(dim), dim = 1; end 
                 27 
  0.27    1063   28   y = sum(x)/size(x,dim); 
           209   29 else 
  4.48     209   30   y = sum(x,dim)/size(x,dim); 
           209   31 end