Mercurial > hg > camir-aes2014
diff toolboxes/FullBNT-1.0.7/bnt/inference/static/@pearl_inf_engine/private/compute_bel.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
---|---|
date | Tue, 10 Feb 2015 15:05:51 +0000 |
parents | |
children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toolboxes/FullBNT-1.0.7/bnt/inference/static/@pearl_inf_engine/private/compute_bel.m Tue Feb 10 15:05:51 2015 +0000 @@ -0,0 +1,24 @@ +function bel = compute_bel(msg_type, pi, lambda) + +switch msg_type, + case 'd', bel = normalise(pi .* lambda); + case 'g', + if isinf(lambda.precision) % ignore pi because lambda is completely certain (observed) + bel.mu = lambda.mu; + bel.Sigma = zeros(length(bel.mu)); % infinite precision => 0 variance + elseif all(pi.Sigma==0) % ignore lambda because pi is completely certain (delta fn prior) + bel.Sigma = pi.Sigma; + bel.mu = pi.mu; + elseif all(isinf(pi.Sigma)) % ignore pi because pi is completely uncertain + bel.Sigma = inv(lambda.precision); + bel.mu = bel.Sigma * lambda.info_state; + elseif all(lambda.precision == 0) % ignore lambda because lambda is completely uncertain + bel.Sigma = pi.Sigma; + bel.mu = pi.mu; + else % combine both pi and lambda + pi_precision = inv(pi.Sigma); + bel.Sigma = inv(pi_precision + lambda.precision); + bel.mu = bel.Sigma*(pi_precision * pi.mu + lambda.info_state); + end + otherwise, error(['unrecognized msg type ' msg_type]) +end