function microtime_float()
{
	if (version_compare(phpversion(), '5.0.0', '>='))
	{
		return microtime(true);
	}
	else
	{
		list($usec, $sec) = explode(' ', microtime());
		return ((float) $usec + (float) $sec);
	}
}
 
$start = microtime_float();