gistfile1.php

function distanceGeoPoints ($long1, $lat1, $long2, $lat2) {
  $lat = deg2rad($lat2 - $lat1);
	$long = deg2rad($long2 - $long1);
	$a = sin($lat/2) * sin($lat/2) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * sin($long/2) * sin($long/2);
	$c = 2 * atan2(sqrt($a), sqrt(1 - $a));
	$d = 6371 * $c;
	
	return $d;
}