annotate toolboxes/FullBNT-1.0.7/bnt/inference/online/@hmm_2TBN_inf_engine/back.m @ 0:e9a9cd732c1e tip

first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
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wolffd@0 1 function b = back(engine, bfuture, f, t)
wolffd@0 2
wolffd@0 3 if f.t ~= t
wolffd@0 4 error('mixed up time stamps')
wolffd@0 5 end
wolffd@0 6
wolffd@0 7 b.t = t;
wolffd@0 8 b.obslik = f.obslik;
wolffd@0 9 bb_future = bfuture.beta .* bfuture.obslik;
wolffd@0 10 if engine.maximize
wolffd@0 11 B = repmat(bb_future(:)', length(bfuture.beta), 1);
wolffd@0 12 b.beta = normalise(max(engine.transprob .* B, [], 2));
wolffd@0 13 else
wolffd@0 14 b.beta = normalise((engine.transprob * bb_future));
wolffd@0 15 end
wolffd@0 16 b.gamma = normalise(f.alpha .* b.beta);
wolffd@0 17 if t > 1
wolffd@0 18 bb_t = b.beta .* b.obslik;
wolffd@0 19 b.xi = normalise((engine.transprob .* (f.past_alpha * bb_t'))); % t-1,t
wolffd@0 20 end
wolffd@0 21