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

PHPSkills/FactorGraphs/FactorList.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Moserware\Skills\FactorGraphs;
+
+/// <summary>
+/// Helper class for computing the factor graph's normalization constant.
+/// </summary>
+class FactorList
+{
+    private $_list = array();
+
+    public function getLogNormalization()
+    {
+        foreach($this->_list as $currentFactor)
+        {
+            $currentFactor->resetMarginals();
+        }
+
+        $sumLogZ = 0.0;
+
+        $listCount = count($this->_list);
+
+        for ($i = 0; $i < $listCount; $i++)
+        {
+            $f = $this->_list[$i];
+
+            $numberOfMessages = $f->getNumberOfMessages();
+
+            for ($j = 0; $j < $numberOfMessages; $j++)
+            {
+                $sumLogZ += $f->sendMessageIndex($j);
+            }
+        }
+
+        $sumLogS = 0;
+
+        foreach($this->_list as $currentFactor)
+        {
+            $sumLogS = $sumLogS + $currentFactor->getLogNormalization();
+        }
+
+        return $sumLogZ + $sumLogS;
+    }
+
+    public function count()
+    {
+        return count($this->_list);
+    }
+
+    public function addFactor(Factor $factor)
+    {
+        $this->_list[] = $factor;
+        return $factor;
+    }
+}
+
+?>