KURV2 - does interpolation for parametric curves

       To use KURV2, load the NCAR Graphics library ngmath.

       Copyright (C) 2000
       University Corporation for Atmospheric Research

       The use of this Software is governed by a License Agreement.

UNIX                                               March 1998                                      KURV2(3NCARG)

       T           (real, input) A value to be mapped to a point on the curve. The interval  [0.,1.]  is  mapped
                   onto  the curve such that 0. is mapped to (X(1),Y(1)) and 1. is mapped to (X(N),Y(N)). Values
                   outside of [0.,1.] result in extrapolation.

       XS          (real, oputput) Contains the X coordinate of the interpolated point that T maps to.

       YS          (real, oputput) Contains the Y coordinate of the interpolated point that T maps to.

       N           (integer, input) The number of input data points. (N > 1)

       X           (real, input) An array containing the X values of the input points.

       Y           (real, input) An array containing the Y values of the input points. Adjacent pairs of  points
                   must be distinct.

       XP          (real, input) An array of length N as computed by KURV1.

       YP          (real, input) An array of length N as computed by KURV1.

       S           (real, input) An array of length N containing the polygonal arc lengths of the curve.

       SIGMA       (real,  input)  Tension factor. Values near zero result in a cubic spline; large values (e.g.
                   50) result in nearly a polygonal line. A typical value is 1.

       KURV2 - does interpolation for parametric curves

       kurv1, fitgrid_params.

       Complete documentation for Fitgrid is available at URL
       http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html

       CALL KURV2 (T, XS, YS, N, X, Y, XP, YP, S, SIGMA)

       The  interpolated  curve is parameterized by mapping points in the interval [0.,1.] onto the interpolated
       curve. The resulting curve has a parametric representation both of whose  components  are  splines  under
       tension  and functions of the polygonal arc length. The value 0. is mapped onto (X[1],Y[1]) and the value
       1. is mapped onto (X[N],Y[N]). KURV1 must be called before calling KURV2.