ncl_curvp2 man page

CURVP2 — interpolate a periodic function at a specified point

Synopsis

FUNCTION CURVP2 (T, N, X, Y, P, YP, SIGMA)

This function interpolates a value at a specified point using a spline  under tension.  CURVP1 must be called prior to calling CURVP2, and the  values thus obtained used as input to CURVP2. CURVP2 returns the interpolated  function value at the X-coordinate specified.

Description

T

(real, input) The abscissa for which an interpolated function value is desired.

N

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

X

(real, input) An array containing the abscissae for the input function.

Y

(real, input) An array containing the functional values of the input  data -- Y(K) is the functional value at X(K) for K=1,N.

X

(real, input) The period of the function.

YP

(real, input) Contains values for the second derivative  (as calculated by CURV1).

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.

Return Value

CURVP2 returns the interpolated value at the specified point T.

Access

To use CURVP2, load the NCAR Graphics library ngmath.

See Also

curvp1, fitgrid_params.

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

Info

March 1998 UNIX NCAR GRAPHICS