private static function calculateNewRating(GameInfo $gameInfo, Rating $selfRating, Rating $opponentRating, $comparison)
{
$drawMargin = DrawMargin::getDrawMarginFromDrawProbability($gameInfo->getDrawProbability(), $gameInfo->getBeta());
$c = sqrt(square($selfRating->getStandardDeviation()) + square($opponentRating->getStandardDeviation()) + 2 * square($gameInfo->getBeta()));
$winningMean = $selfRating->getMean();
$losingMean = $opponentRating->getMean();
switch ($comparison) {
case PairwiseComparison::WIN:
case PairwiseComparison::DRAW:
// NOP
break;
case PairwiseComparison::LOSE:
$winningMean = $opponentRating->getMean();
$losingMean = $selfRating->getMean();
break;
}
$meanDelta = $winningMean - $losingMean;
if ($comparison != PairwiseComparison::DRAW) {
// non-draw case
$v = TruncatedGaussianCorrectionFunctions::vExceedsMarginScaled($meanDelta, $drawMargin, $c);
$w = TruncatedGaussianCorrectionFunctions::wExceedsMarginScaled($meanDelta, $drawMargin, $c);
$rankMultiplier = (int) $comparison;
} else {
$v = TruncatedGaussianCorrectionFunctions::vWithinMarginScaled($meanDelta, $drawMargin, $c);
$w = TruncatedGaussianCorrectionFunctions::wWithinMarginScaled($meanDelta, $drawMargin, $c);
$rankMultiplier = 1;
}
$meanMultiplier = (square($selfRating->getStandardDeviation()) + square($gameInfo->getDynamicsFactor())) / $c;
$varianceWithDynamics = square($selfRating->getStandardDeviation()) + square($gameInfo->getDynamicsFactor());
$stdDevMultiplier = $varianceWithDynamics / square($c);
$newMean = $selfRating->getMean() + $rankMultiplier * $meanMultiplier * $v;
$newStdDev = sqrt($varianceWithDynamics * (1 - $w * $stdDevMultiplier));
return new Rating($newMean, $newStdDev);
}
private function createPriorFactor($player, Rating $priorRating, Variable $skillsVariable)
{
return new GaussianPriorFactor($priorRating->getMean(), square($priorRating->getStandardDeviation()) + square($this->getParentFactorGraph()->getGameInfo()->getDynamicsFactor()), $skillsVariable);
}
public function __construct($rating)
{
parent::__construct($rating, 0);
}
