/// <summary>
/// Computes the angle defined by aBc using Al-Kashi.
/// Warning: this method is not accurate for triangles in spheric environnement.
/// </summary>
/// <param name="point1">The point1.</param>
/// <param name="point2">The point2.</param>
/// <param name="point3">The point3.</param>
/// <returns></returns>
public static double ComputeAngle(LatLong a, LatLong b, LatLong c)
{
if (a == b || a == c || b == c)
{
return(double.NaN);
}
// Al-kashi: alpha = arccos (ab² + bc² - ac² / (2ab * bc))
double abSquare = SquareDistance(a, b);
double bcSquare = SquareDistance(b, c);
double acSquare = SquareDistance(a, c);
return(RadianToDegree
* Math.Acos((abSquare + bcSquare - acSquare) / (2 * Math.Sqrt(abSquare) * Math.Sqrt(bcSquare))));
}
/// <summary>
/// Squares the distance.
/// Warning: this method is poorly accurate.
/// </summary>
/// <param name="point1">The point1.</param>
/// <param name="point2">The point2.</param>
/// <returns></returns>
public static double SquareDistance(LatLong point1, LatLong point2)
{
return(SquareDistance(point1.Latitude, point1.Longitude, point2.Latitude, point2.Longitude));
}
/// <summary>
/// Compute the Haversine distance.
/// </summary>
/// <param name="pointA">The point A.</param>
/// <param name="pointB">The point B.</param>
/// <returns>The distance in kilometers.</returns>
public static double HaversineDistance(LatLong pointA, LatLong pointB)
{
return(HaversineDistance(pointA.Latitude, pointA.Longitude, pointB.Latitude, pointB.Longitude));
}
/// <summary>
/// Gets the distance (in kilometers) between two spherical points (in degrees).
/// Warning: this method is poorly accurate.
/// </summary>
public static double Distance(LatLong point1, LatLong point2)
{
return(DegreeToKilometer(Math.Sqrt(SquareDistance(point1, point2))));
}
