private static Double _MilesToKilometers = 1.609344;
private static Double _MilesToNautical = 0.8684;
/// <summary>
/// Calculates the distance between two points of latitude and longitude.
/// Great Link - http://www.movable-type.co.uk/scripts/latlong.html
/// </summary>
/// <param name="coordinate1">First coordinate.</param>
/// <param name="coordinate2">Second coordinate.</param>
/// <param name="unitsOfLength">Sets the return value unit of length.</param>
public static Double Distance(Coordinate coordinate1, Coordinate coordinate2, UnitsOfLength unitsOfLength)
{
double theta = coordinate1.getLongitude() - coordinate2.getLongitude();
double distance = Math.sin(ToRadian(coordinate1.getLatitude())) * Math.sin(ToRadian(coordinate2.getLatitude())) +
Math.cos(ToRadian(coordinate1.getLatitude())) * Math.cos(ToRadian(coordinate2.getLatitude())) *
Math.cos(ToRadian(theta));
distance = Math.acos(distance);
distance = ToDegree(distance);
distance = distance * 60 * 1.1515;
if (unitsOfLength == UnitsOfLength.Kilometer)
distance = distance * _MilesToKilometers;
else if (unitsOfLength == UnitsOfLength.NauticalMiles)
distance = distance * _MilesToNautical;
return (distance);
}