SYNOPSIS

CALL CURV1 (N, X, Y, SLP1, SLPN, ISLPSW, YP, TEMP, SIGMA, IER)

DESCRIPTION

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).

SLP1

(real, input) A user-specified value for the desired slope at X(1). See ISLPSW below if you want to have a value calculated internally.

SLPN

(real, input) A user-specified value for the desired slope at X(N). See ISLPSW below if you want to have a value calculated internally.

ISLPSW

(integer, input) A switch to indicate whether the slopes at the end points should be calculated internally.

= 0 if SLP1 and SLPN are user-specified.
= 1 if SLP1 is user-specified, but SLPN is internally calculated.
= 2 if SLPN is user-specified, but SLP1 is internally calculated.
= 3 if SLP1 and SLPN are internally calculated.

YP

(real, output) Contains values for the second derivative (CURV1 computes these).

TEMP

(real, input) Scratch space.

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 X values are not strictly increasing.

ACCESS

To use CURV1, load the NCAR Graphics library ngmath.

COPYRIGHT

Copyright (C) 2000
University Corporation for Atmospheric Research

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