diff toolboxes/FullBNT-1.0.7/HMM/dhmm_logprob_path.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/HMM/dhmm_logprob_path.m	Tue Feb 10 15:05:51 2015 +0000
@@ -0,0 +1,15 @@
+function [ll, p] = prob_path(prior, transmat, obsmat, qs)
+% PROB_PATH Compute the prob. of a specific path (state sequence) through an HMM.
+% [ll, p] = prob_path(prior, transmat, obsmat, states)
+%
+% ll = log prob path
+% p(t) = Pr(O(t)) * Pr(Q(t) -> Q(t+1)) for 1<=t<T, p(T) = Pr(O(T))
+
+T = size(obsmat, 2);
+p = zeros(1,T);
+p(1) = prior(qs(1)) * obsmat(qs(1),1);
+for t=2:T
+  p(t) = transmat(qs(t-1), qs(t)) * obsmat(qs(t),t);
+end
+
+ll = sum(log(p));