public double calculateDistance(double latitude1, double longitude1,
			double latitude2, double longitude2) {
		double theta = longitude1 - longitude2;
		double distance = Math.sin(deg2rad(latitude1))
				* Math.sin(deg2rad(latitude2)) + Math.cos(deg2rad(latitude1))
				* Math.cos(deg2rad(latitude2)) * Math.cos(deg2rad(theta));
		distance = Math.acos(distance);
		distance = rad2deg(distance);
		distance = distance * 60 * 1.1515;
		distance = distance * 1.609344;

		return distance;
	}