# dqc25c.f

          SUBROUTINE DQC25C (F, A, B, C, RESULT, ABSERR, KRUL, NEVAL)
    C***BEGIN PROLOGUE  DQC25C
    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      DOUBLE 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        Double precision version
    C
    C        PARAMETERS
    C           F      - Double precision
    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      - Double precision
    C                    Left end point of the integration interval
    C
    C           B      - Double precision
    C                    Right end point of the integration interval, B.GT.A
    C
    C           C      - Double precision
    C                    Parameter in the WEIGHT function
    C
    C           RESULT - Double precision
    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 - Double precision
    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 ......................................................................
    C
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  DQCHEB, DQK15W, DQWGTC
    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  DQC25C