DQCHEB(3)

SYNOPSIS
SUBROUTINE DQCHEB (X, FVAL, CHEB12, CHEB24)

NAME
dqcheb - This routine computes the CHEBYSHEV series expansion of degrees 12 and 24 of a function using A FAST FOURIER TRANSFORM METHOD F(X) = SUM(K=1,..,13) (CHEB12(K)*T(K-1,X)), F(X) = SUM(K=1,..,25) (CHEB24(K)*T(K-1,X)), Where T(K,X) is the CHEBYSHEV POLYNOMIAL OF DEGREE K.

LIBRARY
SLATEC

TYPE
DOUBLE PRECISION (QCHEB-S, DQCHEB-D)

KEYWORDS
CHEBYSHEV SERIES EXPANSION, FAST FOURIER TRANSFORM

AUTHOR
Piessens, Robert Applied Mathematics and Programming Division K. U. Leuven de Doncker, Elise Applied Mathematics and Programming Division K. U. Leuven

DESCRIPTION
Chebyshev Series Expansion Standard Fortran Subroutine Double precision version PARAMETERS ON ENTRY X - Double precision Vector of dimension 11 containing the Values COS(K*PI/24), K = 1, ..., 11 FVAL - Double precision Vector of dimension 25 containing the function values at the points (B+A+(B-A)*COS(K*PI/24))/2, K = 0, ...,24, where (A,B) is the approximation interval. FVAL(1) and FVAL(25) are divided by two (these values are destroyed at output). ON RETURN CHEB12 - Double precision Vector of dimension 13 containing the CHEBYSHEV coefficients for degree 12 CHEB24 - Double precision Vector of dimension 25 containing the CHEBYSHEV Coefficients for degree 24

SEE ALSO
DQC25C, DQC25F, DQC25S

ROUTINES CALLED
(NONE)

REVISION HISTORY (YYMMDD)
810101 DATE WRITTEN
830518 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
900328 Added TYPE section. (WRB)