C
C     ..................................................................
C
C        SUBROUTINE DQL16
C
C        PURPOSE
C           TO COMPUTE INTEGRAL(EXP(-X)*FCT(X), SUMMED OVER X
C                               FROM 0 TO INFINITY).
C
C        USAGE
C           CALL DQL16 (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 16-POINT GAUSSIAN-LAGUERRE
C           QUADRATURE FORMULA, WHICH INTEGRATES EXACTLY,
C           WHENEVER FCT(X) IS A POLYNOMIAL UP TO DEGREE 31.
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 DQL16(FCT,Y)
C
C
      DOUBLE PRECISION X,Y,FCT
C
      X=.51701160339543318D2
      Y=.41614623703728552D-21*FCT(X)
      X=.41940452647688333D2
      Y=Y+.50504737000355128D-17*FCT(X)
      X=.34583398702286626D2
      Y=Y+.62979670025178678D-14*FCT(X)
      X=.28578729742882140D2
      Y=Y+.21270790332241030D-11*FCT(X)
      X=.23515905693991909D2
      Y=Y+.28623502429738816D-9*FCT(X)
      X=.19180156856753135D2
      Y=Y+.18810248410796732D-7*FCT(X)
      X=.15441527368781617D2
      Y=Y+.68283193308711996D-6*FCT(X)
      X=.12214223368866159D2
      Y=Y+.14844586873981299D-4*FCT(X)
      X=.9438314336391939D1
      Y=Y+.20427191530827846D-3*FCT(X)
      X=.70703385350482341D1
      Y=Y+.18490709435263109D-2*FCT(X)
      X=.50780186145497679D1
      Y=Y+.11299900080339453D-1*FCT(X)
      X=.34370866338932066D1
      Y=Y+.47328928694125219D-1*FCT(X)
      X=.21292836450983806D1
      Y=Y+.13629693429637754D0*FCT(X)
      X=.11410577748312269D1
      Y=Y+.26579577764421415D0*FCT(X)
      X=.46269632891508083D0
      Y=Y+.33105785495088417D0*FCT(X)
      X=.8764941047892784D-1
      Y=Y+.20615171495780099D0*FCT(X)
      RETURN
      END
