KURVP1 - calculate values for KURVP2 usage

       To use KURVP1, 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                                     KURVP1(3NCARG)

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

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

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

       XP          (real,output) An array of length N.

       YP          (real,output) An array of length N.

       TEMP        (real,input) Scratch space.

       S           (real,output) An array of length N (this will be used to pass to KURVP2).

       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.

       IER         (integer,output) An error return value. If  IER  is  returned  as  0,  then  no  errors  were
                   detected.

                   = 1 if N is less than 2.
                   = 2 if a pair of adjacent points coincide.

       KURVP1 - calculate values for KURVP2 usage

       kurvp2, fitgrid_params.

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

       CALL KURVP1 (N, X, Y, XP, YP, TEMP, S, SIGMA, IER)

       This  subroutine  calculates  certain values that are used by KURVP2 in order to compute an interpolatory
       spline under tension through a sequence of points in the plane that  form  a  closed  curve.  The  actual
       computation of the interpolated values must be done using KURVP2 .