Mercurial > hg > camir-aes2014
diff toolboxes/FullBNT-1.0.7/bnt/inference/dynamic/@ff_inf_engine/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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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toolboxes/FullBNT-1.0.7/bnt/inference/dynamic/@ff_inf_engine/marginal_family.m Tue Feb 10 15:05:51 2015 +0000 @@ -0,0 +1,44 @@ +function marginal = marginal_family(engine, i, t) +% MARGINAL_FAMILY Compute the marginal on the specified family (ff) +% marginal = marginal_family(engine, i, t) + + +if engine.filter + error('can''t currently use marginal_family when filtering with ff'); +end + +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); +ss = length(bnet.intra); + +if myismember(i, engine.onodes) + ps = parents(bnet.dag, i); + p = ps(1); + marginal = pot_to_marginal(engine.marginals{ps(1),t}); + fam = ([ps i]) + (t-1)*ss; +elseif t==1 + marginal = pot_to_marginal(engine.marginals{i,t}); + fam = i + (t-1)*ss; +else + pot = engine.CPDpot{i,t}; + c = engine.obschild(i); + if c>0 + pot = multiply_by_pot(pot, engine.CPDpot{c,t}); + end + 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)); + fam = ([ps i+ss]) + (t-2)*ss; +end + +% we convert the domain to the unrolled numbering system +% so that update_ess extracts the right evidence. +marginal.domain = fam;