1 files changed, 21 insertions, 0 deletions
diff --git a/sourcecodes/bnt-master/BNT/inference/online/@hmm_2TBN_inf_engine/back.m b/sourcecodes/bnt-master/BNT/inference/online/@hmm_2TBN_inf_engine/back.m
new file mode 100644
index 00000000..8ad416f7
--- /dev/null
+++ b/sourcecodes/bnt-master/BNT/inference/online/@hmm_2TBN_inf_engine/back.m
@@ -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
+