CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCC    Subroutine to calculate the background function 'ftilde'    CCCC 
CCCC    and target mass correction for F1 and F2.                   CCCC   
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
 

      SUBROUTINE SFFIT2(sf,x,q2,bgo,xval,parm2,fn)

      IMPLICIT NONE

      EXTERNAL daind
      DOUBLE PRECISION daind
      EXTERNAL fun
      real*8 fun
      EXTERNAL fun2
      real*8 fun2
      EXTERNAL fun3
      real*8 fun3
      EXTERNAL fun4
      real*8 fun4



      integer i,bgo,sf,kount
      real*8 x,q2,xval(5),parm2(5),ftilde,f1tilde,fn 
      real*8 f10,f20,fL0,g2,h2,xi,ri,a0,a1,a2,mp,mp2
      real*8 tol,est

      COMMON /xparm/ xval2 
      real*8 xval2(5)

      COMMON /xparm3/ xval3 
      real*8 xval3(5)


      mp = 0.9382727
      mp2 = mp*mp
      tol = 1.d0-4

      h2 = 0.d0
      g2 = 0.d0

      do i=1,5 !!!  Make copy of xval array so it doesn't get changed  !!!
        xval2(i) = xval(i)
        xval3(i) = parm2(i) 
      enddo


CCCC    Get background function ftilde as parameterized in function fun(x)  CCCC

      ri = sqrt(1.d0+4.0d0*x*x*mp2/q2)
      xi = 2.0d0*x/(1.0d0+ri)
      ftilde = fun(xi)  

CCCC    Do convolution integrals   CCCC

      if(x.GT.0.001) then    !!! Don't do integration if very low x  !!!
       h2 = daind(xi,1.d0,fun3,tol,2,10000,kount,est) 
       g2 = daind(xi,1.d0,fun4,tol,2,10000,kount,est)
      endif

CCCC    Put together full Structure function including TM terms   CCCCC


      h2 = 2.*mp2/q2*x**3/ri**4*h2
      g2 = 4.*mp2*mp2/q2/q2*x**4/ri**5*g2


      if(sf.EQ.1) then     !!!  Coefficents of terms in expansion  !!! 
          a0 = x*x/ri
          a1 = 2.d0*ri**2 
       else
          a0 = x*x/ri**3
          a1 = 3.d0
       endif 

       fn = a0*ftilde + a1*(h2+g2)


       if(bgo.EQ.1) then 
         fn = fun(x)*x*x 
       endif
      return
      end


CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCC    Parameterization of background function Ftilde           CCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
 
      real*8 function fun(x)
      
      COMMON /xparm/ xval2 
      real*8 xval2(5)

      real*8 x


      fun = xval2(5)*(x)**xval2(1)*(1.d0-x)**xval2(2)*
     &      (1.d0+xval2(3)*sqrt(x)+xval2(4)*x)

      return
      end


CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCC        Function needed to do double integral          CCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 

      real*8 function fun2(xi2)
      IMPLICIT NONE
      EXTERNAL fun
      real*8 fun
      EXTERNAL daind1
      real*8 daind1
      real*8 xi2,tol,est
      integer kount

      tol = 1.d0-4 

      fun2 = daind1(xi2,1.d0,fun,tol,2,10000,kount,est) 
     
      return
      end
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCC    Parameterization of background function Ftilde           CCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
 
      real*8 function fun3(x)
      
      COMMON /xparm3/ xval3  

      real*8 xval3(5)
      real*8 x

      
      fun3 = xval3(5)*(x)**xval3(1)*(1.d0-x)**xval3(2)*
     &      (1.d0+xval3(3)*sqrt(x)+xval3(4)*x)

      return
      end


CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCC        Function needed to do double integral          CCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 

      real*8 function fun4(xi2)
      IMPLICIT NONE
      EXTERNAL fun3
      real*8 fun3
      EXTERNAL daind1
      real*8 daind1
      real*8 xi2,tol,est
      integer kount

      tol = 1.d0-4 
      fun4 = daind1(xi2,1.d0,fun3,tol,2,10000,kount,est)   

      return
      end