ncl_curvp1 - Man Page

CALL CURVP1 (N, X, Y, P, YP, TEMP, SIGMA, IER)

This subroutine calculates certain values that are used by CURVP2 in  order to compute an interpolatory spline under tension through a sequence  of functional values for a periodic function. The actual computation of  the interpolated values must be done using CURVP2 .

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 function -- Y(K) is the functional value at X(K) for K=1,N.

P

(real, input) The period of the function. P must be greater than X(N)-X(1).

YP

(real, output) Contains values for the second derivative (these are  calculated by CURVP1).

TEMP

(real, input) Scratch space.

SIGMA

(integer, 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 P is less than or equal to X(N)-X(1).
= 3 if the X values are not strictly increasing.

To use CURVP1, load the NCAR Graphics library ngmath.

curvp2, fitgrid_params.

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

Copyright (C) 2000
University Corporation for Atmospheric Research

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