dqcheb.f
SUBROUTINE DQCHEB (X, FVAL, CHEB12, CHEB24)
C***BEGIN PROLOGUE DQCHEB
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Warning: this routine is not intended to be user-callable.
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C***SUBSIDIARY
C***PURPOSE This routine computes the CHEBYSHEV series expansion
C of degrees 12 and 24 of a function using A
C FAST FOURIER TRANSFORM METHOD
C F(X) = SUM(K=1,..,13) (CHEB12(K)*T(K-1,X)),
C F(X) = SUM(K=1,..,25) (CHEB24(K)*T(K-1,X)),
C Where T(K,X) is the CHEBYSHEV POLYNOMIAL OF DEGREE K.
C***LIBRARY SLATEC
C***TYPE DOUBLE PRECISION (QCHEB-S, DQCHEB-D)
C***KEYWORDS CHEBYSHEV SERIES EXPANSION, FAST FOURIER TRANSFORM
C***AUTHOR Piessens, Robert
C Applied Mathematics and Programming Division
C K. U. Leuven
C de Doncker, Elise
C Applied Mathematics and Programming Division
C K. U. Leuven
C***DESCRIPTION
C
C Chebyshev Series Expansion
C Standard Fortran Subroutine
C Double precision version
C
C PARAMETERS
C ON ENTRY
C X - Double precision
C Vector of dimension 11 containing the
C Values COS(K*PI/24), K = 1, ..., 11
C
C FVAL - Double precision
C Vector of dimension 25 containing the
C function values at the points
C (B+A+(B-A)*COS(K*PI/24))/2, K = 0, ...,24,
C where (A,B) is the approximation interval.
C FVAL(1) and FVAL(25) are divided by two
C (these values are destroyed at output).
C
C ON RETURN
C CHEB12 - Double precision
C Vector of dimension 13 containing the
C CHEBYSHEV coefficients for degree 12
C
C CHEB24 - Double precision
C Vector of dimension 25 containing the
C CHEBYSHEV Coefficients for degree 24
C
C***SEE ALSO DQC25C, DQC25F, DQC25S
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 810101 DATE WRITTEN
C 830518 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900328 Added TYPE section. (WRB)
C***END PROLOGUE DQCHEB