# 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/f…

## Copyright

Copyright (C) 2000

University Corporation for Atmospheric Research

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

## Info

NCAR GRAPHICS August 2002