function y = mean(x,dim)
%MEAN   Average or mean value.
%   For vectors, MEAN(X) is the mean value of the elements in X. For
%   matrices, MEAN(X) is a row vector containing the mean value of
%   each column.  For N-D arrays, MEAN(X) is the mean value of the
%   elements along the first non-singleton dimension of X.
%
%   MEAN(X,DIM) takes the mean along the dimension DIM of X. 
%
%   Example: If X = [0 1 2
%                    3 4 5]
%
%   then mean(X,1) is [1.5 2.5 3.5] and mean(X,2) is [1

if prod(size(x))==1, y = x; return, end

if nargin==1, 
  dim = min(find(size(x)~=1));
  if isempty(dim), dim = 1; end
end

if ~isempty(x),
  y = sum(x,dim)/size(x,dim);
else
  y = NaN;
end