Start of factor graph port. Things don't work yet, but a lot of syntax updates towards PHP

PHPSkills/TrueSkill/Factors/GaussianFactor.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace Moserware\Skills\TrueSkill\Factors;
+
+abstract class GaussianFactor extends Factor
+{
+    protected function __construct($name)
+    {
+        parent::__construct($name);
+    }
+
+    /// 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);
+        $variable->setValue($marginal*$messageValue);
+        return $logZ;
+    }
+
+    public function createVariableToMessageBinding(Variable $variable)
+    {
+        return parent::createVariableToMessageBinding($variable,
+                                                      new Message(
+                                                          GaussianDistribution::fromPrecisionMean(0, 0),
+                                                          "message from {0} to {1}", $this));
+    }
+}
+
+
+?>