function stats=summary_stats(x)
% Usage:
%   stats=summary_stats(x)
%
% This function takes an input matrix X and returns a size(X,2) by 4 matrix
% contyainsng the mean, standard deviation, skewness and kurtosis where 
% each row of the output contains results correspnding to a column of the input.
%
%  The order of the outputs are
%     mean   std dev.   skewness   kurtosis
%
stats=[mean(x)' std(x)' skewness(x)' kurtosis(x)'];