private double getDistance(Angle startLatitude, Angle startLongitude, Angle endLatitude, Angle endLongitude, double radius)
{
Angle angularDistance = SMath.ApproxAngularDistance(startLatitude, startLongitude, endLatitude, endLongitude);
int steps = 4;
double distance = 0;
Vector3d d1 = SMath.SphericalToCartesianV3D(startLatitude.Degrees, startLongitude.Degrees, radius);
for (int i = 1; i < steps; i++)
{
Angle curLat;
Angle curLon;
SMath.IntermediateGCPoint((float)i / (float)(steps - 1), startLatitude, startLongitude, endLatitude, endLongitude, angularDistance, out curLat, out curLon);
Vector3d d2 = SMath.SphericalToCartesianV3D(curLat.Degrees, curLon.Degrees, radius);
Vector3d segment = d2 - d1;
distance += segment.Length;
d1 = d2;
}
return(distance);
}