wolffd@0: function [fwd, loglik] = filter_evidence(engine, CPDpot, observed, pot_type)
wolffd@0: % [fwd, loglik] = filter_evidence(engine, CPDpot, observed, pot_type) (ff)
wolffd@0: 
wolffd@0: [ss T] = size(CPDpot);
wolffd@0: fwd = cell(ss,T);
wolffd@0: hnodes = engine.hnodes(:)';
wolffd@0: onodes = engine.onodes(:)';
wolffd@0: bnet = bnet_from_engine(engine);
wolffd@0: ns = bnet.node_sizes;
wolffd@0: onodes2 = [onodes onodes+ss];
wolffd@0: ns(onodes2) = 1;
wolffd@0: 
wolffd@0: logscale = zeros(1,T);
wolffd@0: H = length(hnodes);
wolffd@0: local_logscale = zeros(1,ss);
wolffd@0:   
wolffd@0: t = 1;
wolffd@0: for i=hnodes
wolffd@0:   fwd{i,t} = CPDpot{i,t};
wolffd@0:   c = engine.obschild(i);
wolffd@0:   if c > 0
wolffd@0:     fwd{i,t} = multiply_by_pot(fwd{i,t}, CPDpot{c, t});
wolffd@0:   end
wolffd@0:   [fwd{i,t}, local_logscale(i)] = normalize_pot(fwd{i,t});
wolffd@0: end
wolffd@0: logscale(t) = sum(local_logscale);
wolffd@0: 
wolffd@0: for t=2:T
wolffd@0:   for i=hnodes
wolffd@0:     ps = parents(bnet.dag, i+ss);
wolffd@0:     assert(all(ps<=ss)); % in previous slice
wolffd@0:     prior = CPDpot{i,t};
wolffd@0:     for p=ps(:)'
wolffd@0:       prior = multiply_by_pot(prior, fwd{p,t-1});
wolffd@0:     end
wolffd@0:     fwd{i,t} = marginalize_pot(prior, i+ss);
wolffd@0:     fwd{i,t} = set_domain_pot(fwd{i,t}, i);
wolffd@0:     c = engine.obschild(i);
wolffd@0:     if c > 0
wolffd@0:       fwd{i,t} = multiply_by_pot(fwd{i,t}, CPDpot{c,t});
wolffd@0:     end
wolffd@0:     [fwd{i,t}, local_logscale(i)] = normalize_pot(fwd{i,t});
wolffd@0:   end
wolffd@0:   logscale(t) = sum(local_logscale);
wolffd@0: end
wolffd@0: 
wolffd@0: loglik = sum(logscale);
wolffd@0: