/// Factor representing a team difference that has exceeded the draw margin. /// /// See the accompanying math paper for more details. class GaussianGreaterThanFactor extends GaussianFactor { private $_epsilon; public function __construct($epsilon, Variable &$variable) { parent::__construct(\sprintf("%s > %.2f", $variable, $epsilon)); $this->_epsilon = $epsilon; $this->createVariableToMessageBinding($variable); } 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)/ $messageFromVariable->getStandardDeviation())); } protected function updateMessageVariable(Message &$message, Variable &$variable) { $oldMarginal = clone $variable->getValue(); $oldMessage = clone $message->getValue(); $messageFromVar = GaussianDistribution::divide($oldMarginal, $oldMessage); $c = $messageFromVar->getPrecision(); $d = $messageFromVar->getPrecisionMean(); $sqrtC = sqrt($c); $dOnSqrtC = $d/$sqrtC; $epsilsonTimesSqrtC = $this->_epsilon*$sqrtC; $d = $messageFromVar->getPrecisionMean(); $denom = 1.0 - TruncatedGaussianCorrectionFunctions::wExceedsMargin($dOnSqrtC, $epsilsonTimesSqrtC); $newPrecision = $c/$denom; $newPrecisionMean = ($d + $sqrtC* TruncatedGaussianCorrectionFunctions::vExceedsMargin($dOnSqrtC, $epsilsonTimesSqrtC))/ $denom; $newMarginal = GaussianDistribution::fromPrecisionMean($newPrecisionMean, $newPrecision); $newMessage = GaussianDistribution::divide( GaussianDistribution::multiply($oldMessage, $newMarginal), $oldMarginal); /// Update the message and marginal $message->setValue($newMessage); $variable->setValue($newMarginal); /// Return the difference in the new marginal return GaussianDistribution::subtract($newMarginal, $oldMarginal); } } ?>