A nonuniform rational B-Spline curve defined by
where is the order, are the B-Spline basis functions, are control points, and
the weight of is the last ordinate of the homogeneous point . These curves are
closed under perspective transformations and can represent Conic Sections exactly.
See also B-Spline, Bézier Curve, NURBS Surface
Piegl, L. and Tiller, W. The NURBS Book, 2nd ed New York: Springer-Verlag, 1997.
© 1996-9 Eric W. Weisstein