Question

I am using this code to calculate the the distance between two points. I am using the Haversine formula

private double CalcDistance(Location Start, Location End) 
    {
        // TODO Auto-generated method stub
        double distance;
        double lat1 = Start.getLatitude();
        double lat2 = End.getLatitude();
        double lng1 = Start.getLongitude();
        double lng2 = End.getLongitude();
        double dLat = Math.abs(Math.toRadians(lat2-lat1));
        double dLng = Math.abs(Math.toRadians(lng2 - lng1));

        distance = Math.sin(dLat/2) * Math.sin(dLng/2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * 
                Math.sin(dLng/2) * Math.sin(dLng/2);

        double c = 2 * Math.asin(Math.sqrt(distance));

        //Return the answer in Kilometre (6371km the mean radius of the earth)
        return c * 6371;
    }

The valus that is produced only changes if the Longitude of the Location is changed and stays the same if the Latitude is changed. Is there any reason my code only does this.

Answer 1

Hey I’m not entirely sure, but just looking at your code you might have made an error, I dont understand it but perhaps you could change

distance = Math.sin(dLat/2) * Math.sin(dLng/2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * 
                Math.sin(dLng/2) * Math.sin(dLng/2);

to

distance = 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);