="fragment"><pre class="comment"> COXDER computes derivatives of basis splines by Cox-de Boor recursion. It
 is assumed that N is the output of COX(x,pk), i.e., its first row
 contains the function values at x. This function fills out the second row
 with the first derivative. The 2nd to pth derivatives are not yet
 implemented.
 N: (p+1)x(p+1) matrix, return value of COX(x,p,k).
 knotSpan: knot span of the abscissae, return value of COX(x,p,k)
 k: knot vector
 Nout: overwritten array N</pre></div>

<!-- cr