wolffd@0: function lam_msg = CPD_to_lambda_msg(CPD, msg_type, n, ps, msg, p, evidence)
wolffd@0: % CPD_TO_LAMBDA_MSG Compute lambda message (discrete)
wolffd@0: % lam_msg = compute_lambda_msg(CPD, msg_type, n, ps, msg, p, evidence)
wolffd@0: % Pearl p183 eq 4.52
wolffd@0: 
wolffd@0: switch msg_type
wolffd@0:   case 'd',
wolffd@0:    T = prod_CPT_and_pi_msgs(CPD, n, ps, msg, p);
wolffd@0:    mysize = length(msg{n}.lambda);
wolffd@0:    lambda = dpot(n, mysize, msg{n}.lambda);
wolffd@0:    T = multiply_by_pot(T, lambda);
wolffd@0:    lam_msg = pot_to_marginal(marginalize_pot(T, p));
wolffd@0:    lam_msg = lam_msg.T;           
wolffd@0:  case 'g',
wolffd@0:   error('discrete_CPD can''t create Gaussian msgs')
wolffd@0: end