web development helpdesk

The Spherical law of cosines gives a pretty accurate result that will be sufficient for most applications.

/**
    lat, longs are in radians
*/
public static double distance(double lat1, double lon1, 
                                              double lat2, double lon2) {
    return R * Math.acos(Math.sin(lat1) * Math.sin(lat2) +
        Math.cos(lat1) * Math.cos(lat2) * Math.cos(lon1 - lon2));
}

private static final double R = 6371.0;  // earths mean radius in km

written by objects \\ tags: distance, latitude, longitude