Home > freetb4matlab > nurbs > nrbderiv.m

nrbderiv

PURPOSE ^

SYNOPSIS ^

function dnurbs = nrbderiv(nurbs)

DESCRIPTION ^

 
 NRBDERIV: Construct the first derivative representation of a
           NURBS curve or surface.
 
 Calling Sequence:
 
   ders = nrbderiv(nrb);
 
 Parameters:
 
   nrb        : NURBS data structure, see nrbmak.
 
   ders    : A data structure that represents the first
           derivatives of a NURBS curve or surface.
 
 Description:
 
   The derivatives of a B-Spline are themselves a B-Spline of lower degree,
   giving an efficient means of evaluating multiple derivatives. However,
   although the same approach can be applied to NURBS, the situation for
   NURBS is a more complex. I have at present restricted the derivatives
   to just the first. I don't claim that this implentation is
   the best approach, but it will have to do for now. The function returns
   a data struture that for a NURBS curve contains the first derivatives of
   the B-Spline representation. Remember that a NURBS curve is represent by
   a univariate B-Spline using the homogeneous coordinates.
   The derivative data structure can be evaluated later with the function
   nrbdeval.
 
 Examples:
 
   See the function nrbdeval for an example.
 
 See:
 
       nrbdeval

CROSS-REFERENCE INFORMATION ^

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