File DQH48.FT (FORTRAN source file)

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C
C     ..................................................................
C
C        SUBROUTINE DQH48
C
C        PURPOSE
C           TO COMPUTE INTEGRAL(EXP(-X*X)*FCT(X), SUMMED OVER X FROM
C                               -INFINITY TO +INFINITY).
C
C        USAGE
C           CALL DQH48 (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 48-POINT GAUSSIAN-HERMITE
C           QUADRATURE FORMULA, WHICH INTEGRATES EXACTLY WHENEVER
C           FCT(X) IS A POLYNOMIAL UP TO DEGREE 95.
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.213-214.
C
C     ..................................................................
C
      SUBROUTINE DQH48(FCT,Y)
C
C
      DOUBLE PRECISION X,Y,Z,FCT
C
      X=.8975315081931687D1
      Z=-X
      Y=.7935551460773997D-35*(FCT(X)+FCT(Z))
      X=.8310752190704784D1
      Z=-X
      Y=Y+.59846126933138784D-30*(FCT(X)+FCT(Z))
      X=.7759295519765775D1
      Z=-X
      Y=Y+.36850360801506699D-26*(FCT(X)+FCT(Z))
      X=.7266046554164350D1
      Z=-X
      Y=Y+.55645774689022848D-23*(FCT(X)+FCT(Z))
      X=.68100645780741414D1
      Z=-X
      Y=Y+.31883873235051384D-20*(FCT(X)+FCT(Z))
      X=.63805640961864106D1
      Z=-X
      Y=Y+.8730159601186677D-18*(FCT(X)+FCT(Z))
      X=.59710722250135454D1
      Z=-X
      Y=Y+.13151596226584085D-15*(FCT(X)+FCT(Z))
      X=.55773169812237286D1
      Z=-X
      Y=Y+.11975898654791794D-13*(FCT(X)+FCT(Z))
      X=.51962877187923645D1
      Z=-X
      Y=Y+.70469325815458891D-12*(FCT(X)+FCT(Z))
      X=.48257572281332095D1
      Z=-X
      Y=Y+.28152965378381691D-10*(FCT(X)+FCT(Z))
      X=.44640145469344589D1
      Z=-X
      Y=Y+.7930467495165382D-9*(FCT(X)+FCT(Z))
      X=.41097046035605902D1
      Z=-X
      Y=Y+.16225141358957698D-7*(FCT(X)+FCT(Z))
      X=.37617264902283578D1
      Z=-X
      Y=Y+.24686589936697505D-6*(FCT(X)+FCT(Z))
      X=.34191659693638846D1
      Z=-X
      Y=Y+.28472586917348481D-5*(FCT(X)+FCT(Z))
      X=.30812489886451058D1
      Z=-X
      Y=Y+.25285990277484889D-4*(FCT(X)+FCT(Z))
      X=.27473086248223832D1
      Z=-X
      Y=Y+.17515043180117283D-3*(FCT(X)+FCT(Z))
      X=.24167609048732165D1
      Z=-X
      Y=Y+.9563923198194153D-3*(FCT(X)+FCT(Z))
      X=.20890866609442764D1
      Z=-X
      Y=Y+.41530049119775525D-2*(FCT(X)+FCT(Z))
      X=.17638175798953000D1
      Z=-X
      Y=Y+.14444961574981099D-1*(FCT(X)+FCT(Z))
      X=.14405252201375652D1
      Z=-X
      Y=Y+.40479676984603849D-1*(FCT(X)+FCT(Z))
      X=.11188121524021566D1
      Z=-X
      Y=Y+.9182229707928518D-1*(FCT(X)+FCT(Z))
      X=.7983046277785622D0
      Z=-X
      Y=Y+.16920447194564111D0*(FCT(X)+FCT(Z))
      X=.47864633759449610D0
      Z=-X
      Y=Y+.25396154266475910D0*(FCT(X)+FCT(Z))
      X=.15949293584886247D0
      Z=-X
      Y=Y+.31100103037796308D0*(FCT(X)+FCT(Z))
      RETURN
      END



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