Mercurial > hg > camir-aes2014
comparison 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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-1:000000000000 | 0:e9a9cd732c1e |
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1 function marginal = marginal_family(engine, i, t) | |
2 % MARGINAL_FAMILY Compute the marginal on the specified family (ff) | |
3 % marginal = marginal_family(engine, i, t) | |
4 | |
5 if nargin < 3, t = 1; end | |
6 | |
7 % The method is similar to the following HMM equation: | |
8 % xi(i,j,t) = normalise( alpha(i,t) * transmat(i,j) * obsmat(j,t+1) * beta(j,t+1) ) | |
9 % where xi(i,j,t) = Pr(Q(t)=i, Q(t+1)=j | y(1:T)) | |
10 | |
11 bnet = bnet_from_engine(engine); | |
12 | |
13 if myismember(i, engine.onodes) | |
14 ps = parents(bnet.dag, i); | |
15 p = ps(1); | |
16 marginal = pot_to_marginal(engine.marginals{p,t}); | |
17 marginal.domain = [p i]; | |
18 return; | |
19 end | |
20 | |
21 if t==1 | |
22 marginal = pot_to_marginal(engine.marginals{i,t}); | |
23 return; | |
24 end | |
25 | |
26 bnet = bnet_from_engine(engine); | |
27 ss = length(bnet.intra); | |
28 pot = engine.CPDpot{i,t}; | |
29 c = engine.obschild(i); | |
30 pot = multiply_by_pot(pot, engine.CPDpot{c,t}); | |
31 pot = multiply_by_pot(pot, engine.back{i,t}); | |
32 ps = parents(bnet.dag, i+ss); | |
33 for p=ps(:)' | |
34 pot = multiply_by_pot(pot, engine.fwd{p,t-1}); | |
35 end | |
36 marginal = pot_to_marginal(normalize_pot(pot)); | |
37 | |
38 |