Provided by: libncarg-dev_6.3.0-6build1_amd64

**NAME**

CURVD - derivatives for 1D functions.

**SYNOPSIS**

FUNCTION CURVD (T, N, X, Y, YP, SIGMA) This function calculates a derivative at a specified point using a spline under tension. CURV1 must be called prior to calling CURVD, and the values thus obtained used as input to CURVD. The derivative value is returned.

**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. 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**

CURVD returns the derivative value of the interpolated curve at the specified point T.

**ACCESS**

To use CURVD, load the NCAR Graphics library ngmath.

**SEE** **ALSO**

curv1, fitgrid_params. Complete documentation for Fitgrid is available at URL http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html

**COPYRIGHT**

Copyright (C) 2000 University Corporation for Atmospheric Research The use of this Software is governed by a License Agreement.