NRBSURFDERIVEVAL: Evaluate n-th order derivatives of a NURBS surface.


 usage: skl = nrbsurfderiveval (srf, [u; v], d) 

   INPUT  :

    srf   : NURBS surface structure, see nrbmak

    u, v  : parametric coordinates of the point where we compute the
      derivatives

    d     : number of partial derivatives to compute

   OUTPUT :

    skl (i, j, k, l) = i-th component derived j-1,k-1 times at the
      l-th point.

 Adaptation of algorithm A4.4 from the NURBS book

Package: nurbs