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

first hg version after svn

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolboxes/FullBNT-1.0.7/bnt/inference/online/@hmm_2TBN_inf_engine/back.m	Tue Feb 10 15:05:51 2015 +0000
@@ -0,0 +1,21 @@
+function b = back(engine, bfuture, f, t)
+
+if f.t ~= t
+  error('mixed up time stamps')
+end
+
+b.t = t;
+b.obslik = f.obslik;
+bb_future = bfuture.beta .* bfuture.obslik;
+if engine.maximize
+  B = repmat(bb_future(:)', length(bfuture.beta), 1);
+  b.beta = normalise(max(engine.transprob .* B, [], 2));
+else
+  b.beta = normalise((engine.transprob * bb_future));
+end
+b.gamma = normalise(f.alpha .* b.beta);
+if t > 1
+  bb_t = b.beta .* b.obslik;
+  b.xi = normalise((engine.transprob .* (f.past_alpha * bb_t'))); % t-1,t
+end
+