function [nec] = NEC(data,allmodel)
% NEC - 
% 
% The mathematical definition of this function is given on Epage 163-164
% 
% Inputs: 
%   allmodel = the output from the EDA toolbox function mbclust.m
% 
% Written by:
% -- 
% John L. Weatherwax                2009-03-24
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

nec = zeros(length(allmodel),length(allmodel(end).clus)); 
for mi=1:length(allmodel)
  L = zeros(1,length(allmodel(mi).clus));
  for ki=1:length(allmodel(mi).clus)
  
    pies = allmodel(mi).clus(ki).pies; 
    mus  = allmodel(mi).clus(ki).mus; 
    vars = allmodel(mi).clus(ki).vars; 

    [clabs3,unc,all_posts,den_estimate] = mixclass( data, pies, mus, vars ); 
  
    % calculate C(K): 
    pi_times_f_hat = pies(:) * den_estimate.';
    tau_times_ln   = all_posts .* log( pi_times_f_hat.' );
    C_k = sum(tau_times_ln(:)); 
    
    % calculate E(K): 
    tau_times_ln = all_posts .* log( all_posts+1e-6 ); 
    E_k = -sum(tau_times_ln(:)); 
    
    % calculate L(K): 
    L(ki) = C_k + E_k; 
    
    if( ki==1 )
      nec(mi,ki) = 1; 
    else
      nec(mi,ki) = E_k / ( L(ki) - L(1) ); 
    end
    
  end

end