<?php function CalculateDistance($lat1, $lon1, $lat2, $lon2, $distanceType)
{

$theta = $lon1 – $lon2;
$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
$dist = acos($dist);
$dist = rad2deg($dist);
$miles = $dist * 60 * 1.1515;
$distanceType = strtoupper($distanceType);

if ($distanceType == “K”)
{
//return distance in kilometers
return ($miles * 1.609344);
}
else
{
//return distance in miles
return $miles;
}
}?>