function [ED2 A]=transD2(tc,T)
%TRANSD2   Expected (Translated) (L2Distance)^2
%
%   Arguments:
%      TC          document term counts (NOT normalized); assumed that all
%                     documents contain at least one word
%      T           translation matrix
%
%   Returns:
%      ED2         E_{p(y|x)} ( ||x_i-x_j||_2^2 )
%      A           E_{p(y|x)} ( ||x_i||_2^2 )
%
%   Authors:
%       Joshua V. Dillon; Feb. 21, 2007; jvdillon AAT purdue DDOT edu

if nargin~=2
	error('insufficient arguments');
end

[Mv,Nd]=size(tc);

N   = sum(tc,1)';
TT  = T*T';
%TT  = diag(ones(Mv,1));	% jvd: debug: should result in ||x-y||_2^2
B   = tc' * TT * tc;
%A   = (N.^-2) .* diag(B - tc'*diag(TT)*h') + N.^-1;		% jvd: old way
A   = (N.^-2) .* (diag(B) - tc'*diag(TT)) + N.^-1;


% jvd: lce06 errata -1 not -2
%ED2 = A*h' + h*A' - 2 * diag(N.^-1) * B * diag(N.^-1);	% jvd: old way
ED2 = repmat(A,1,Nd) + repmat(A',Nd,1) - 2 * diag(N.^-1) * B * diag(N.^-1);