distance between 2 gps location

gpsdistance

static double EARTH_RADIUS = 6378100;// radius of earth in meters

public static double gpsdistance (double lat1, double long1, double lat2, double long2)
    {
		//in meters :D
        double degToRad= Math.PI / 180.0;
        double phi1 = lat1 * degToRad;
        double phi2 = lat2 * degToRad;
        double lam1 = long1 * degToRad;
        double lam2 = long2 * degToRad;

        return EARTH_RADIUS * Math.acos( Math.sin(phi1) * Math.sin(phi2) + Math.cos(phi1) * Math.cos(phi2) * Math.cos(lam2 - lam1) );
    }