subroutine d9upak (x, y, n)
c august 1980 portable edition.  w. fullerton, los alamos scientific lab
c
c unpack floating point number x so that x = y * 2.0**n, where
c 0.5 .le. abs(y) .lt. 1.0 .
c
      double precision x, y, absx
c
      absx = dabs(x)
      n = 0
      y = 0.0d0
      if (x.eq.0.0d0) return
c
 10   if (absx.ge.0.5d0) go to 20
      n = n - 1
      absx = absx*2.0d0
      go to 10
c
 20   if (absx.lt.1.0d0) go to 30
      n = n + 1
      absx = absx*0.5d0
      go to 20
c
 30   y = dsign (absx, x)
      return
c
      end