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Text File  |  1985-11-29  |  3KB  |  93 lines
  1. C
  2. C     ..................................................................
  3. C
  4. C        SUBROUTINE DQL24
  5. C
  6. C        PURPOSE
  7. C           TO COMPUTE INTEGRAL(EXP(-X)*FCT(X), SUMMED OVER X
  8. C                               FROM 0 TO INFINITY).
  9. C
  10. C        USAGE
  11. C           CALL DQL24 (FCT,Y)
  12. C           PARAMETER FCT REQUIRES AN EXTERNAL STATEMENT
  13. C
  14. C        DESCRIPTION OF PARAMETERS
  15. C           FCT    - THE NAME OF AN EXTERNAL DOUBLE PRECISION FUNCTION
  16. C                    SUBPROGRAM USED.
  17. C           Y      - THE RESULTING DOUBLE PRECISION INTEGRAL VALUE.
  18. C
  19. C        REMARKS
  20. C           NONE
  21. C
  22. C        SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED
  23. C           THE EXTERNAL DOUBLE PRECISION FUNCTION SUBPROGRAM FCT(X)
  24. C           MUST BE FURNISHED BY THE USER.
  25. C
  26. C        METHOD
  27. C           EVALUATION IS DONE BY MEANS OF 24-POINT GAUSSIAN-LAGUERRE
  28. C           QUADRATURE FORMULA, WHICH INTEGRATES EXACTLY,
  29. C           WHENEVER FCT(X) IS A POLYNOMIAL UP TO DEGREE 47.
  30. C           FOR REFERENCE, SEE
  31. C           SHAO/CHEN/FRANK, TABLES OF ZEROS AND GAUSSIAN WEIGHTS OF
  32. C           CERTAIN ASSOCIATED LAGUERRE POLYNOMIALS AND THE RELATED
  33. C           GENERALIZED HERMITE POLYNOMIALS, IBM TECHNICAL REPORT
  34. C           TR00.1100 (MARCH 1964), PP.24-25.
  35. C
  36. C     ..................................................................
  37. C
  38.       SUBROUTINE DQL24(FCT,Y)
  39. C
  40. C
  41.       DOUBLE PRECISION X,Y,FCT
  42. C
  43.       X=.8149827923394889D2
  44.       Y=.55753457883283568D-34*FCT(X)
  45.       X=.69962240035105030D2
  46.       Y=Y+.40883015936806578D-29*FCT(X)
  47.       X=.61058531447218762D2
  48.       Y=Y+.24518188458784027D-25*FCT(X)
  49.       X=.53608574544695070D2
  50.       Y=Y+.36057658645529590D-22*FCT(X)
  51.       X=.47153106445156323D2
  52.       Y=Y+.20105174645555035D-19*FCT(X)
  53.       X=.41451720484870767D2
  54.       Y=Y+.53501888130100376D-17*FCT(X)
  55.       X=.36358405801651622D2
  56.       Y=Y+.7819800382459448D-15*FCT(X)
  57.       X=.31776041352374723D2
  58.       Y=Y+.68941810529580857D-13*FCT(X)
  59.       X=.27635937174332717D2
  60.       Y=Y+.39177365150584514D-11*FCT(X)
  61.       X=.23887329848169733D2
  62.       Y=Y+.15070082262925849D-9*FCT(X)
  63.       X=.20491460082616425D2
  64.       Y=Y+.40728589875499997D-8*FCT(X)
  65.       X=.17417992646508979D2
  66.       Y=Y+.7960812959133630D-7*FCT(X)
  67.       X=.14642732289596674D2
  68.       Y=Y+.11513158127372799D-5*FCT(X)
  69.       X=.12146102711729766D2
  70.       Y=Y+.12544721977993333D-4*FCT(X)
  71.       X=.9912098015077706D1
  72.       Y=Y+.10446121465927518D-3*FCT(X)
  73.       X=.7927539247172152D1
  74.       Y=Y+.67216256409354789D-3*FCT(X)
  75.       X=.61815351187367654D1
  76.       Y=Y+.33693490584783036D-2*FCT(X)
  77.       X=.46650837034671708D1
  78.       Y=Y+.13226019405120157D-1*FCT(X)
  79.       X=.33707742642089977D1
  80.       Y=Y+.40732478151408646D-1*FCT(X)
  81.       X=.22925620586321903D1
  82.       Y=Y+.9816627262991889D-1*FCT(X)
  83.       X=.14255975908036131D1
  84.       Y=Y+.18332268897777802D0*FCT(X)
  85.       X=.7660969055459366D0
  86.       Y=Y+.25880670727286980D0*FCT(X)
  87.       X=.31123914619848373D0
  88.       Y=Y+.25877410751742390D0*FCT(X)
  89.       X=.59019852181507977D-1
  90.       Y=Y+.14281197333478185D0*FCT(X)
  91.       RETURN
  92.       END
  93.