distance between lat and long

Return the distance in miles or kilometers by inputting two lat and long point into the function with either a "K" or "M" for unit.

function distance($lat1, $lon1, $lat2, $lon2, $unit) {
	$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;
	$unit = strtoupper($unit);
	if ($unit == "K") {
		return ($miles * 1.609344);
	} else if ($unit == "N") {
		return ($miles * 0.8684);
	} else {
		return $miles;
	}
}