# ncl_curvs2 man page

CURVS2 — calculates an interpolated value for a smoothing spline under tension at a given point.

## Synopsis

FUNCTION CURVS2(T,N,PARAM,X,Y,XP,YP,SIGMA,XO,YO)

This subroutine is a companion to CURV1S which must be called before calling this subroutine. CURV2S calculates an interpolated value for a smoothing spline under tension at a given point.

## Description

- T
(real, input) A real value to be mapped onto the interpolating curve. Values of T between zero and one interpolate the original data; any values of T outside this range result in extrapolation.

- N
(integer, input) The number of points which were specified to determine the curve in CURVS1.

- PARAM
(real, input) The arc lengths as computed by CURVS1.

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

- Y
(real, input) An array containing the Y-coordinate values of the specified points.

- XP
(real, input) An array of second derivative values as calculated by CURVS1.

- YP
(real, input) An array of second derivative values as calculated by CURVS1.

- 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.

- XO
(real, output) The interpolated X value.

- YO
(real, output) The interpolated Y value.

## Access

To use CURV2, load the NCAR Graphics library ngmath.

## See Also

curvs1, 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.