code: public Double haversine(Position other) {
  		double lon0r = toRadians(this.longitude);
  		double lat0r = toRadians(this.latitude);
  		double lon1r = toRadians(other.longitude);
  		double lat1r = toRadians(other.latitude);
  		double a = pow(sin((lat1r - lat0r) / 2.0), 2);
  		double b = cos(lat0r) * cos(lat1r) * pow(sin((lon1r - lon0r) / 2.0), 2);
  
  		return 6371000.0 * 2 * asin(sqrt(a + b));
  	}
docs: Calculates the two-dimensional great circle distance (haversine)
  @param other position to which we calculate the distance
  @return distance between the this and other position in meters