NAME

       KURVP1 - calculate values for KURVP2 usage

SYNOPSIS

       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
       .

DESCRIPTION

       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.

ACCESS

       To use KURVP1, load the NCAR Graphics library ngmath.

SEE ALSO

       kurvp2, fitgrid_params.

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

COPYRIGHT

       Copyright (C) 2000
       University Corporation for Atmospheric Research

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