function [pdf]=distribution_b(X,cbins)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Function  [pdf]=distribution_b(X,cbins)
% 
%   estimates probability density function from histogram, specifying bins
%
%   inputs : X, timeseries (or matrix of column-vector timseries)
%            cbins , center of bins vector
%   outputs : pdf (normalized)
%           
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
if size(X,1)~= 1
    X=X';
end
N=length(X);
%compute histogram
[his]=hist(X,cbins);
pdf=his/sum(his);