# ncl_kurvp1 - Man Page

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.