Largest palindrome product

palindrome.php

<?php
/*
 * Largest palindrome product
 */

$max = 0;

$output = null;
for ($i = 100; $i < 10000; $i++ ) {
  for ($j = 100; $j < 10000; $j++) {
    $mul = $i*$j;
    if ($mul == strrev($mul) && $mul > $max) {
      $max = $mul;
    }
  }
}

echo "$max\n";