mirror of
https://github.com/furyfire/trueskill.git
synced 2025-11-04 02:02:29 +01:00
83 lines
3.2 KiB
PHP
83 lines
3.2 KiB
PHP
<?php
|
|
namespace Moserware\Skills\TrueSkill\Factors;
|
|
|
|
require_once(dirname(__FILE__) . "GaussianFactor.php");
|
|
require_once(dirname(__FILE__) . "../TruncatedGaussianCorrectionFunctions.php");
|
|
require_once(dirname(__FILE__) . "../../FactorGraphs/Message.php");
|
|
require_once(dirname(__FILE__) . "../../FactorGraphs/Variable.php");
|
|
require_once(dirname(__FILE__) . "../../Numerics/GaussianDistribution.php");
|
|
|
|
use Moserware\Numerics\GaussianDistribution;
|
|
use Moserware\Skills\TrueSkill\TruncatedGaussianCorrectionFunctions;
|
|
use Moserware\Skills\FactorGraphs\Message;
|
|
use Moserware\Skills\FactorGraphs\Variable;
|
|
|
|
/// <summary>
|
|
/// Factor representing a team difference that has not exceeded the draw margin.
|
|
/// </summary>
|
|
/// <remarks>See the accompanying math paper for more details.</remarks>
|
|
class GaussianWithinFactor extends GaussianFactor
|
|
{
|
|
private $_epsilon;
|
|
|
|
public function __construct($epsilon, Variable $variable)
|
|
{
|
|
$this->_epsilon = $epsilon;
|
|
$this->createVariableToMessageBinding($variable);
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
protected function updateMessage(Message $message, Variable $variable)
|
|
{
|
|
$oldMarginal = clone $variable->getValue();
|
|
$oldMessage = clone $message->getValue();
|
|
$messageFromVariable = GaussianDistribution::divide($oldMarginal, $oldMessage);
|
|
|
|
$c = $messageFromVariable->getPrecision();
|
|
$d = $messageFromVariable->getPrecisionMean();
|
|
|
|
$sqrtC = sqrt($c);
|
|
$dOnSqrtC = $d/$sqrtC;
|
|
|
|
$epsilonTimesSqrtC = $this->_epsilon*$sqrtC;
|
|
$d = $messageFromVariable->getPrecisionMean();
|
|
|
|
$denominator = 1.0 - TruncatedGaussianCorrectionFunctions::wWithinMargin($dOnSqrtC, $epsilonTimesSqrtC);
|
|
$newPrecision = $c/$denominator;
|
|
$newPrecisionMean = ($d +
|
|
$sqrtC*
|
|
TruncatedGaussianCorrectionFunctions::vWithinMargin($dOnSqrtC, $epsilonTimesSqrtC))/
|
|
$denominator;
|
|
|
|
$newMarginal = GaussianDistribution::fromPrecisionMean($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);
|
|
}
|
|
}
|
|
|
|
?>
|