Android code Menghitung jarak (Haverstain)

Menghitung dua buah kordinat secara earthRadius menggunakan Havertsain:

public static double distFrom(double lat1, double lng1, double lat2, double lng2) {

           double earthRadius = 3958.75;

           double dLat = Math.toRadians(lat2-lat1);

           double dLng = Math.toRadians(lng2-lng1);

           double a = Math.sin(dLat/2) * Math.sin(dLat/2) +

                      Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *

                      Math.sin(dLng/2) * Math.sin(dLng/2);

           double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

           double dist = earthRadius * c;

           int meterConversion = 1609;

           double myjr=dist * meterConversion;

           return Math.floor(myjr/1000);

           }