# ncl_curv1 man page

CURV1 — does set-up for CURV2.

## 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.

## See Also

curv2, 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 March 1998