KPG1_CHE2X

Evaluates a two-dimensional Chebyshev polynomial

Description:

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

Invocation

CALL KPG1_CHE2X( NPTS, XMIN, XMAX, X, YMIN, YMAX, Y, XDEG, YDEG, NCOEF, CC, NW, WORK, EVAL, STATUS )

Arguments

NPTS = INTEGER (Given)
The number of evaluations to perform at constant Y position.
XMIN = ? (Given)
The lower endpoint of the range of the fit along the first dimension. 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 along the second dimension. See XMIN.
X( NPTS ) = ? (Given)
The co-ordinates along the first dimension for which the Chebyshev polynomial is to be evaluated.
YMIN = ? (Given)
The lower endpoint of the range of the fit along the first dimension. The Chebyshev series representation is in terms of a normalised variable, evaluated as (2y - (YMAX + YMIN) ) / (YMAX - YMIN), where y is the original variable. YMIN must be less than YMAX.
YMAX = ? (Given)
The upper endpoint of the range of the fit along the second dimension. See YMIN.
Y = ? (Given)
The co-ordinate along the second dimension for which the Chebyshev polynomial is to be evaluated.
XDEG = INTEGER (Given)
The degree of the polynomial along the first dimension.
YDEG = INTEGER (Given)
The degree of the polynomial along the second dimension.
NCOEF = INTEGER (Given)
The number of coefficients. This must be at least the product of (XDEG+1) ∗ (YDEG+1).
CC( NCOEF ) = ? (Given)
The Chebyshev coefficients. These should be the order such that CCij is in CC( i∗(YDEG+1)+j+1 ) for i=0,XDEG; j=0,YDEG. In other words the opposite order to Fortran standard.
NW = INTEGER (Given)
The number of elements in the work array. It must be at least XDEG + 1.
WORK( NW ) = ? (Returned)
Workspace.
EVAL( NPTS ) = ? (Returned)
The evaluated polynomial for the supplied arguments. Should an argument lie beyond the range ([XMIN,XMAX], [YMIN,YMAX] 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, X, YMIN, YMAX, Y, CC, WORK, and EVAL arguments supplied to the routine must have the data type specified.