Distance between two locations isn't right

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

Check H开发者_运维问答aversine 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;

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.

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.

public double CalculationByDistance(GeoPoint StartP, GeoPoint EndP) {  
  double lat1 = StartP.getLatitudeE6()/1E6;  
  double lat2 = EndP.getLatitudeE6()/1E6;  
  double lon1 = StartP.getLongitudeE6()/1E6;  
  double lon2 = EndP.getLongitudeE6()/1E6;  
  double dLat = Math.toRadians(lat2-lat1);  
  double dLon = Math.toRadians(lon2-lon1);  
  double 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.asin(Math.sqrt(a));  
  return Radius * c;  
 }  

Ally your concept was right.May be a little bit chang in this line double c = 2 * Math.asin(Math.sqrt(a));