Mercurial > hg > camir-aes2014
view toolboxes/FullBNT-1.0.7/bnt/inference/dynamic/@ff_inf_engine/Old/marginal_family.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
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date | Tue, 10 Feb 2015 15:05:51 +0000 |
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function marginal = marginal_family(engine, i, t) % MARGINAL_FAMILY Compute the marginal on the specified family (ff) % marginal = marginal_family(engine, i, t) if nargin < 3, t = 1; end % The method is similar to the following HMM equation: % xi(i,j,t) = normalise( alpha(i,t) * transmat(i,j) * obsmat(j,t+1) * beta(j,t+1) ) % where xi(i,j,t) = Pr(Q(t)=i, Q(t+1)=j | y(1:T)) bnet = bnet_from_engine(engine); if myismember(i, engine.onodes) ps = parents(bnet.dag, i); p = ps(1); marginal = pot_to_marginal(engine.marginals{p,t}); marginal.domain = [p i]; return; end if t==1 marginal = pot_to_marginal(engine.marginals{i,t}); return; end bnet = bnet_from_engine(engine); ss = length(bnet.intra); pot = engine.CPDpot{i,t}; c = engine.obschild(i); pot = multiply_by_pot(pot, engine.CPDpot{c,t}); pot = multiply_by_pot(pot, engine.back{i,t}); ps = parents(bnet.dag, i+ss); for p=ps(:)' pot = multiply_by_pot(pot, engine.fwd{p,t-1}); end marginal = pot_to_marginal(normalize_pot(pot));