Get distance of locations

Hi
I have many locations(about 1000 location)
I need calculate distance between this location
My code is :

PHP Code:

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 (strtolower($unit) == "k") {
            return ($miles * 1.609344);
        } else if ($unit == "N") {
            return ($miles * 0.8684);
        } else {
            return $miles;
        }
    } 


I calculate distance between two location with foreach

PHP Code:

foreach($result as $row) {

            if ($current != NULL) {
                $distance += distance($current['latitude'],$current['longitude'],$row['latitude'],$row['longitude'],'k') ;
                $current    =   $row;
            } else {
                $current    =   $row;
            }

        } 


In each loop,i save previous location and get distance from their
But it is wrong
Does anybody can help me?