C
C     ..................................................................
C
C        SUBROUTINE DQL8
C
C        PURPOSE
C           TO COMPUTE INTEGRAL(EXP(-X)*FCT(X), SUMMED OVER X
C                               FROM 0 TO INFINITY).
C
C        USAGE
C           CALL DQL8 (FCT,Y)
C           PARAMETER FCT REQUIRES AN EXTERNAL STATEMENT
C
C        DESCRIPTION OF PARAMETERS
C           FCT    - THE NAME OF AN EXTERNAL DOUBLE PRECISION FUNCTION
C                    SUBPROGRAM USED.
C           Y      - THE RESULTING DOUBLE PRECISION INTEGRAL VALUE.
C
C        REMARKS
C           NONE
C
C        SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED
C           THE EXTERNAL DOUBLE PRECISION FUNCTION SUBPROGRAM FCT(X)
C           MUST BE FURNISHED BY THE USER.
C
C        METHOD
C           EVALUATION IS DONE BY MEANS OF 8-POINT GAUSSIAN-LAGUERRE
C           QUADRATURE FORMULA, WHICH INTEGRATES EXACTLY,
C           WHENEVER FCT(X) IS A POLYNOMIAL UP TO DEGREE 15.
C           FOR REFERENCE, SEE
C           SHAO/CHEN/FRANK, TABLES OF ZEROS AND GAUSSIAN WEIGHTS OF
C           CERTAIN ASSOCIATED LAGUERRE POLYNOMIALS AND THE RELATED
C           GENERALIZED HERMITE POLYNOMIALS, IBM TECHNICAL REPORT
C           TR00.1100 (MARCH 1964), PP.24-25.
C
C     ..................................................................
C
      SUBROUTINE DQL8(FCT,Y)
C
C
      DOUBLE PRECISION X,Y,FCT
C
      X=.22863131736889264D2
      Y=.10480011748715104D-8*FCT(X)
      X=.15740678641278005D2
      Y=Y+.8485746716272532D-6*FCT(X)
      X=.10758516010180995D2
      Y=Y+.9076508773358213D-4*FCT(X)
      X=.70459054023934657D1
      Y=Y+.27945362352256725D-2*FCT(X)
      X=.42667001702876588D1
      Y=Y+.33343492261215652D-1*FCT(X)
      X=.22510866298661307D1
      Y=Y+.17579498663717181D0*FCT(X)
      X=.9037017767993799D0
      Y=Y+.41878678081434296D0*FCT(X)
      X=.17027963230510100D0
      Y=Y+.36918858934163753D0*FCT(X)
      RETURN
      END
