PDA_SPLEV - Evaluate spline, given in its B-spline representation from PDA_CURFIT.

Origin

DIERCKX / NETLIB

      subroutine pda_splev(t,n,c,k,x,y,m,ier)


  subroutine pda_splev evaluates in a number of points x(i),i=1,2,...,m
  a spline s(x) of degree k, given in its b-spline representation.

  calling sequence:
     call pda_splev(t,n,c,k,x,y,m,ier)

  input parameters:
    t    : array,length n, which contains the position of the knots.
    n    : integer, giving the total number of knots of s(x).
    c    : array,length n, which contains the b-spline coefficients.
    k    : integer, giving the degree of s(x).
    x    : array,length m, which contains the points where s(x) must
           be evaluated.
    m    : integer, giving the number of points where s(x) must be
           evaluated.

  output parameter:
    y    : array,length m, giving the value of s(x) at the different
           points.
    ier  : error flag
      ier = 0 : normal return
      ier =10 : invalid input data (see restrictions)

  restrictions:
    m >= 1
    t(k+1) <= x(i) <= x(i+1) <= t(n-k) , i=1,2,...,m-1.

  other subroutines required: pda_fpbspl.

  references :
    de boor c  : on calculating with b-splines, j. approximation theory
                 6 (1972) 50-62.
    cox m.g.   : the numerical evaluation of b-splines, j. inst. maths
                 applics 10 (1972) 134-149.
    dierckx p. : curve and surface fitting with splines, monographs on
                 numerical analysis, oxford university press, 1993.

  author :
    p.dierckx
    dept. computer science, k.u.leuven
    celestijnenlaan 200a, b-3001 heverlee, belgium.
    e-mail : Paul.Dierckx@cs.kuleuven.ac.be

  latest update : march 1987