Distance between two longitude and latitude

// The distance between two longitude and latitude ranges from private final double earth_radius = 6378137.0; private double gps2m (double lat_a, double lng_a, double lat_ B, double lng_ B) {double radlat1 = (lat_a * Math. (PI/180.0); double radlat2 = (lat_ B * Math. PI/180.0); Double A = radlat1-radlat2; Double B = (lng_a-lng_ B) * Math. PI/180.0; double S = 2 * Math. asin (math. SQRT (math. pow (math. sin (A/2), 2) + math. cos (radlat1) * Math. cos (radlat2) * Math. pow (math. sin (B/2), 2); s = S * earth_radius; S = math. round (S * 10000)/10000; return s ;}