/**
* Method uses the haversine formulae
* to calculate the distance around the
* globe from one city to another.
* @return - distance in miles
*/
public double calcDistanceToFly()
{
double R = 6371000;
double lat1 = OriginCity.getLatitude();
double lat2 = destinationcity.getLatitude();
double lon1 = OriginCity.getLongitude();
double lon2 = destinationcity.getLongitude();
double lat1Radians = Math.PI * (lat1);
double lat2Radians = Math.PI * (lat2);
double lon1Radians = Math.PI * (lon1);
double lon2Radians = Math.PI * (lon2);
double deltaLat = Math.PI * (lat2 - lat1);
double deltaLon = Math.PI * (lon2 - lon1);
double a = Math.Pow(Math.Sin(deltaLat / 2), 2) + (Math.Cos(lat1Radians) * Math.Cos(lat2Radians) * Math.Pow(Math.Sin(deltaLon / 2), 2));
double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
double distance = R * c;
return(distance * 0.000621371);
} //end
