public override Base GetBase()
{
Base B = ModelMatrix.toBase();
B.BaseO = Point;
if (Lam >= 0)
{
xyz D = ModelMatrix * Curve.Derivation(Lam) - ModelMatrix * new xyz(0, 0, 0);
B = Base.DoComplete(Point, D, new xyz(0, 0, 1) & D);
}
return(B);
}