PHP - Gravatar API Function

<?php
function show_my_gravatar($email, $size, $default, $rating)
{
  $params = '?gravatar_id='.md5($email).'&default='.$default.'&size='.$size.'&rating='.$rating;
  $output = '<img src="http://www.gravatar.com/avatar.php'.$params.'" width="'.$size.'px" height="'.$size.'px" />';
  echo $output;
}
?>