KPG1_CHEVx

Evaluates a one-dimensional Chebyshev polynomial

Description:

This routine evaluates a one-dimensional Chebyshev polynomial for one or more arguments. It uses Clenshaw’ s recurrence relationship.

Invocation

CALL KPG1_CHEVx( XMIN, XMAX, NCOEF, CHCOEF, NPTS, X, EVAL, STATUS )

Arguments

XMIN = ? (Given)
The lower endpoint of the range of the fit. The Chebyshev series representation is in terms of a normalised variable, evaluated as ( 2x - (XMAX + XMIN) ) / (XMAX - XMIN), where x is the original variable. XMIN must be less than XMAX.
XMAX = ? (Given)
The upper endpoint of the range of the fit. See XMIN.
NCOEF = INTEGER (Given)
The number of coefficients. This must be at least the polynomial order plus one.
CC( NCOEF ) = ? (Given)
The Chebyshev coefficients.
NPTS = INTEGER (Given)
The number of arguments for which the Chebyshev polynomial is to be evaluated.
X( NPTS ) = ? (Given)
The arguments for which the Chebyshev polynomial is to be evaluated.
EVAL( NPTS ) = ? (Returned)
The evaluated polynomial for the supplied arguments. Should an argument lie beyond the range [XMIN,XMAX], the bad value is returned in the corresponding element of EVAL.
STATUS = INTEGER (Given and Returned)
The global status.

Notes:

There is a routine for the real and double precision data types: replace " x" in the routine name by R or D respectively. The XMIN, XMAX, CC, X, and EVAL arguments supplied to the routine must have the data type specified.