program fvalue

C     SCALAR ARGUMENTS
      integer i
      double precision seed

C     LOCAL SCALARS
      double precision drand,nran


      do i = 1,20

      seed = i

      nran  = drand(seed)

      write(*,*) i,nran
      
      end do

      end

C     ******************************************************************
C     ******************************************************************

      double precision function drand(ix)
      double precision ix

      double precision a,p,b15,b16,xhi,xalo,leftlo,fhi,k
      data a/16807.d0/,b15/32768.d0/,b16/65536.d0/,p/2147483647.d0/

      xhi= ix/b16
      xhi= xhi - dmod(xhi,1.d0)
      xalo= (ix-xhi*b16)*a
      leftlo= xalo/b16
      leftlo= leftlo - dmod(leftlo,1.d0)
      fhi= xhi*a + leftlo
      k= fhi/b15
      k= k - dmod(k,1.d0)
      ix= (((xalo-leftlo*b16)-p)+(fhi-k*b15)*b16)+k
      if (ix.lt.0) ix= ix + p
      drand= ix*4.656612875d-10

      return

      end