qc25c.f
SUBROUTINE QC25C (F, A, B, C, RESULT, ABSERR, KRUL, NEVAL)
C***BEGIN PROLOGUE QC25C
C***PURPOSE To compute I = Integral of F*W over (A,B) with
C error estimate, where W(X) = 1/(X-C)
C***LIBRARY SLATEC (QUADPACK)
C***CATEGORY H2A2A2, J4
C***TYPE SINGLE PRECISION (QC25C-S, DQC25C-D)
C***KEYWORDS 25-POINT CLENSHAW-CURTIS INTEGRATION, QUADPACK, QUADRATURE
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 Integration rules for the computation of CAUCHY
C PRINCIPAL VALUE integrals
C Standard fortran subroutine
C Real version
C
C PARAMETERS
C F - Real
C Function subprogram defining the integrand function
C F(X). The actual name for F needs to be declared
C E X T E R N A L in the driver program.
C
C A - Real
C Left end point of the integration interval
C
C B - Real
C Right end point of the integration interval, B.GT.A
C
C C - Real
C Parameter in the WEIGHT function
C
C RESULT - Real
C Approximation to the integral
C result is computed by using a generalized
C Clenshaw-Curtis method if C lies within ten percent
C of the integration interval. In the other case the
C 15-point Kronrod rule obtained by optimal addition
C of abscissae to the 7-point Gauss rule, is applied.
C
C ABSERR - Real
C Estimate of the modulus of the absolute error,
C which should equal or exceed ABS(I-RESULT)
C
C KRUL - Integer
C Key which is decreased by 1 if the 15-point
C Gauss-Kronrod scheme has been used
C
C NEVAL - Integer
C Number of integrand evaluations
C
C***REFERENCES (NONE)
C***ROUTINES CALLED QCHEB, QK15W, QWGTC
C***REVISION HISTORY (YYMMDD)
C 810101 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890531 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C***END PROLOGUE QC25C