public override Vector2d GetThirdDerivative(double t)
{
CurveDerivatives cd = new CurveDerivatives();
cd.init(false, false, false, true);
Get(t, ref cd);
return(cd.d3);
}
public override Vector2D GetSecondDerivative(double t)
{
CurveDerivatives cd = new CurveDerivatives();
cd.init(false, false, true, false);
Get(t, ref cd);
return(cd.d2);
}