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fixed em log likelihood

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This commit is contained in:
Maria Dimashova 2012-04-06 17:06:35 +00:00
parent b8c310065c
commit 84aff376a7
1 changed files with 2 additions and 1 deletions
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modules/ml/src/em.cpp
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@ -485,6 +485,7 @@ void EM::computeProbabilities(const Mat& sample, int& label, Mat* probs, float*
exp(L, expL); exp(L, expL);
float partExpSum = 0, // sum_j!=q (exp(L_jk) float partExpSum = 0, // sum_j!=q (exp(L_jk)
factor; // 1/(1 + sum_j!=q (exp(L_jk)) factor; // 1/(1 + sum_j!=q (exp(L_jk))
float prevL = expL.at<float>(label);
for(int clusterIndex = 0; clusterIndex < nclusters; clusterIndex++) for(int clusterIndex = 0; clusterIndex < nclusters; clusterIndex++)
{ {
if(clusterIndex != label) if(clusterIndex != label)
@ -504,7 +505,7 @@ void EM::computeProbabilities(const Mat& sample, int& label, Mat* probs, float*
if(likelihood) if(likelihood)
{ {
// note likelihood = log (sum_j exp(L_ij)) - 0.5 * dims * ln2Pi // note likelihood = log (sum_j exp(L_ij)) - 0.5 * dims * ln2Pi
*likelihood = std::log(partExpSum + expL.at<float>(label)) - (float)(0.5 * dim * CV_LOG2PI); *likelihood = std::log(prevL + partExpSum) - (float)(0.5 * dim * CV_LOG2PI);
} }
} }