<?php
echo "preg_match (a?)<sup>n</sup>a<sup>n</sup> on a<sup>n</sup>...<br/>";

$regex = "";
$haystack = "";

ini_set( "pcre.recursion_limit", 100000 );

for( $i = 1; $i < 50; $i++ ){
  $regex = "a?".$regex."a";
  $haystack = "a".$haystack;
  $time_start = microtime(true);
  $result = preg_match("/".$regex."/",$haystack);
  $time_end = microtime(true);
  $time = $time_end - $time_start;
  if( $result === FALSE ){
    echo "BULLSHIT! ";
  }
  echo "i = $i: ".number_format($time,5)." seconds, answer: $result<br/>";
}
?>