/**=========================================================================
	 * CLASS CONSTANTS
	 * 
	 * Constants used throughout this program and their comments.
	 *========================================================================*/
    public static final double RADIUS = 3956.6;
	
    
	/**=========================================================================
	 * CLASS METHODS
	 * 
	 * Program methods are listed below in alphabetical order or the order in
	 * which they are used in main below.
	 *========================================================================*/
    
    /**
	 * Returns spherical distance in miles between two points
	 * @param lat1  - Latitude of first point
	 * @param long1 - Longitude of first point
	 * @param lat2 - Latitude of second point
	 * @param long2 - longitude of second point
	 * @return
	 */
	public static double calculateDistance(double lat1, double long1,
										   double lat2, double long2) {
		lat1 = Math.toRadians(lat1);
		long1 = Math.toRadians(long1);
		lat2 = Math.toRadians(lat2);
		long2 = Math.toRadians(long2);
		double theCos = Math.sin(lat1) * Math.sin(lat2) +
				        Math.cos(lat1) * Math.cos(lat2) *
				        Math.cos(long1 - long2);
		double arcLength = Math.acos(theCos);
		return arcLength * RADIUS;
		
	}