/**
* Sends the factor-graph message with and returns the log-normalization constant.
*/
protected function sendMessageVariable(Message $message, Variable $variable)
{
$marginal = $variable->getValue();
$messageValue = $message->getValue();
$logZ = GaussianDistribution::logProductNormalization($marginal, $messageValue);
$variable->setValue(GaussianDistribution::multiply($marginal, $messageValue));
return $logZ;
}
public function getLogNormalization()
{
$vars = $this->getVariables();
$marginal = $vars[0]->getValue();
$messages = $this->getMessages();
$message = $messages[0]->getValue();
$messageFromVariable = GaussianDistribution::divide($marginal, $message);
return -GaussianDistribution::logProductNormalization($messageFromVariable, $message) + log(GaussianDistribution::cumulativeTo(($messageFromVariable->getMean() - $this->_epsilon) / $messageFromVariable->getStandardDeviation()));
}
public function testLogProductNormalization()
{
// Verified with Ralf Herbrich's F# implementation
$standardNormal = new GaussianDistribution(0, 1);
$lpn = GaussianDistribution::logProductNormalization($standardNormal, $standardNormal);
$this->assertEquals(-1.2655121234846454, $lpn, '', GaussianDistributionTest::ERROR_TOLERANCE);
$m1s2 = new GaussianDistribution(1, 2);
$m3s4 = new GaussianDistribution(3, 4);
$lpn2 = GaussianDistribution::logProductNormalization($m1s2, $m3s4);
$this->assertEquals(-2.5168046699816684, $lpn2, '', GaussianDistributionTest::ERROR_TOLERANCE);
}
public function getLogNormalization()
{
$variables =& $this->getVariables();
$marginal =& $variables[0]->getValue();
$messages =& $this->getMessages();
$message =& $messages[0]->getValue();
$messageFromVariable = GaussianDistribution::divide($marginal, $message);
$mean = $messageFromVariable->getMean();
$std = $messageFromVariable->getStandardDeviation();
$z = GaussianDistribution::cumulativeTo(($this->_epsilon - $mean) / $std) - GaussianDistribution::cumulativeTo((-$this->_epsilon - $mean) / $std);
return -GaussianDistribution::logProductNormalization($messageFromVariable, $message) + log($z);
}
