Mercurial > hg > camir-aes2014
annotate toolboxes/FullBNT-1.0.7/bnt/inference/static/@pearl_inf_engine/private/compute_bel.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
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date | Tue, 10 Feb 2015 15:05:51 +0000 |
parents | |
children |
rev | line source |
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wolffd@0 | 1 function bel = compute_bel(msg_type, pi, lambda) |
wolffd@0 | 2 |
wolffd@0 | 3 switch msg_type, |
wolffd@0 | 4 case 'd', bel = normalise(pi .* lambda); |
wolffd@0 | 5 case 'g', |
wolffd@0 | 6 if isinf(lambda.precision) % ignore pi because lambda is completely certain (observed) |
wolffd@0 | 7 bel.mu = lambda.mu; |
wolffd@0 | 8 bel.Sigma = zeros(length(bel.mu)); % infinite precision => 0 variance |
wolffd@0 | 9 elseif all(pi.Sigma==0) % ignore lambda because pi is completely certain (delta fn prior) |
wolffd@0 | 10 bel.Sigma = pi.Sigma; |
wolffd@0 | 11 bel.mu = pi.mu; |
wolffd@0 | 12 elseif all(isinf(pi.Sigma)) % ignore pi because pi is completely uncertain |
wolffd@0 | 13 bel.Sigma = inv(lambda.precision); |
wolffd@0 | 14 bel.mu = bel.Sigma * lambda.info_state; |
wolffd@0 | 15 elseif all(lambda.precision == 0) % ignore lambda because lambda is completely uncertain |
wolffd@0 | 16 bel.Sigma = pi.Sigma; |
wolffd@0 | 17 bel.mu = pi.mu; |
wolffd@0 | 18 else % combine both pi and lambda |
wolffd@0 | 19 pi_precision = inv(pi.Sigma); |
wolffd@0 | 20 bel.Sigma = inv(pi_precision + lambda.precision); |
wolffd@0 | 21 bel.mu = bel.Sigma*(pi_precision * pi.mu + lambda.info_state); |
wolffd@0 | 22 end |
wolffd@0 | 23 otherwise, error(['unrecognized msg type ' msg_type]) |
wolffd@0 | 24 end |