A simple function that takes two GPS coordinates as input and outputs the distance between them in meter. More approaches can be found here

private double gps2m(float lat_a, float lng_a, float lat_b, float lng_b) {
float pk = (float) (180/3.14169);
float a1 = lat_a / pk;
float a2 = lng_a / pk;
float b1 = lat_b / pk;
float b2 = lng_b / pk;
float t1 = FloatMath.cos(a1)*FloatMath.cos(a2)*FloatMath.cos(b1)*FloatMath.cos(b2);
float t2 = FloatMath.cos(a1)*FloatMath.sin(a2)*FloatMath.cos(b1)*FloatMath.sin(b2);
float t3 = FloatMath.sin(a1)*FloatMath.sin(b1);
double tt = Math.acos(t1 + t2 + t3);
return 6366000*tt;
}

## 7 Comments

This only works if the points are close enough that you can omit that earth is not regular shape. Google has an API that works correctly even on a longer distance, but you have to make a HTTP request to get this.

It's not perfect, but you can use this function (C#) to approximate the average ellipsoid radius between points:

ellipsoidRadius = 6378.137 * (1 - 0.0033493 * Math.Pow(Math.Sin(0.5 * (Lat1 + Lat2)), 2));

Beats making an HTTP request for each calculation, especially for mobile apps.

You can simply use the API function for this:

http://developer.android.com/reference/android/location/Location.html#distanceTo(android.location.Location)

Just thought I'd point out that PI is actually 3.14159 not 3.14169.

Location.distanceBetween gives meters + bearing.

Quite inspiring,

Anyway, thanks for the post

API DistanceTo and Bearing To are quite imperfect unless your 2 locations points are 100 meter apart at least