Distance between two locations isn't right

Question

I have used the algorithm on http://www.movable-type.co.uk/scripts/latlong.html to find the distance between two points.

My two points are

long1 = 51.507467;
lat1 = -0.08776;

long2 = 51.508736;
lat2 = -0.08612;

According to Movable Type Script the answer is 0.1812km

My application gives the result (d) as 0.230km

// Haversine formula: (http://www.movable-type.co.uk/scripts/latlong.html)
    double R = 6371; // earth’s radius (mean radius = 6,371km)
    double dLat =  Math.toRadians(lat2-lat1);

    double dLon =  Math.toRadians(long2-long1); 
    a = Math.sin(dLat/2) * Math.sin(dLat/2) +
            Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * 
            Math.sin(dLon/2) * Math.sin(dLon/2); 
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
    double d = R * c;

Answer 1

Your implementation is correct. The distance given those longitudes and latitudes should produce a distance of 0.230 km. The normal input for coordinates, however, is (latitude, longitude). Putting them in backwards (longitude, latitude) produces the incorrect distance of 0.1812 km.

Answer 2

Why to reinvent your own distance calculator, there is one built into the Location class.

Check out

distanceBetween(double startLatitude, double startLongitude, double endLatitude, double endLongitude, float[] results) 
Computes the approximate distance in meters between two locations, and optionally the initial and final bearings of the shortest path between them.