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annotate toolboxes/FullBNT-1.0.7/bnt/CPDs/@tabular_CPD/log_prior.m @ 0:e9a9cd732c1e tip

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first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
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wolffd@0 1 function L = log_prior(CPD)
wolffd@0 2 % LOG_PRIOR Return log P(theta) for a tabular CPD
wolffd@0 3 % L = log_prior(CPD)
wolffd@0 4
wolffd@0 5 switch CPD.prior_type
wolffd@0 6 case 'none',
wolffd@0 7 L = 0;
wolffd@0 8 case 'dirichlet',
wolffd@0 9 D = CPD.dirichlet(:);
wolffd@0 10 L = sum(log(D + (D==0)));
wolffd@0 11 case 'entropic',
wolffd@0 12 % log-prior = log exp(-H(theta)) = sum_i theta_i log (theta_i)
wolffd@0 13 fam_sz = CPD.sizes;
wolffd@0 14 psz = prod(fam_sz(1:end-1));
wolffd@0 15 ssz = fam_sz(end);
wolffd@0 16 C = reshape(CPD.CPT, psz, ssz);
wolffd@0 17 L = sum(sum(C .* log(C + (C==0))));
wolffd@0 18 end