Daniel@0: function logp = enumerate_HMM_loglik(prior, transmat, obsmat)
Daniel@0: % ENUMERATE_HMM_LOGLIK Compute the log likelihood of a sequence by exhaustive (O(Q^T)) enumeration.
Daniel@0: % logp = enumerate_HMM_loglik(prior, transmat, obsmat)
Daniel@0: %
Daniel@0: % Inputs:
Daniel@0: % prior(i) = Pr(Q(1) = i)
Daniel@0: % transmat(i,j) = Pr(Q(t+1)=j | Q(t)=i)
Daniel@0: % obsmat(i,t) = Pr(y(t) | Q(t)=i)
Daniel@0: 
Daniel@0: Q = length(prior);
Daniel@0: T = size(obsmat, 2);
Daniel@0: sizes = repmat(Q, 1, T);
Daniel@0: 
Daniel@0: psum = 0;
Daniel@0: for i=1:Q^T
Daniel@0:   qs = ind2subv(sizes, i); % make the state sequence 
Daniel@0:   psum = psum + prob_path(prior, transmat, obsmat, qs);
Daniel@0: end
Daniel@0: logp = log(psum)
Daniel@0: 
Daniel@0: