php function to find Relative time in year, month, week, day etc

<?php
//function to find time passed or time left between two time.from & to are two arguments.
//to is optional and defaults to current time stamp if not given
echo time_relative("May 3, 1985 4:20 PM");
//convert time to maonth days weeks
 function time_relative($from, $to = null)
 {
  $to = (($to === null) ? (time()) : ($to));
  $to = ((is_int($to)) ? ($to) : (strtotime($to)));
  $from = ((is_int($from)) ? ($from) : (strtotime($from)));
  $output = '';

  $units = array
  (
   "year"   => 29030400, // seconds in a year   (12 months)
   "month"  => 2419200,  // seconds in a month  (4 weeks)
   "week"   => 604800,   // seconds in a week   (7 days)
   "day"    => 86400,    // seconds in a day    (24 hours)
   "hour"   => 3600,     // seconds in an hour  (60 minutes)  
   "minute" => 60,       // seconds in a minute (60 seconds)
   "second" => 1         // 1 second
  );

  $diff = abs($from - $to);
  $suffix = (($from > $to) ? ("left") : ("old"));

  foreach($units as $unit => $mult)
   if($diff >= $mult)
   {
    $and = (($mult != 1) ? ("") : ("and "));
    $output .= ", ".$and.intval($diff / $mult)." ".$unit.((intval($diff / $mult) == 1) ? ("") : ("s"));
    $diff -= intval($diff / $mult) * $mult;
   }
  $output .= " ".$suffix;
  $output = substr($output, strlen(", "));

  return $output;
 }
 ?>