subroutine sort(a, n)
c
c -- bubble sort routine for vector a
c -- figure 6.3
c     
      integer n, i, j, n1, i1
      real a(1), hold
c
      n1 = n - 1
      do 20 i = 1, n1
       i1 = i + 1
       do 10 j = i1, n
        if (a(i) .le. a(j)) goto 10
        hold = a(i)
        a(i) = a(j)
        a(j) = hold
10     continue
20    continue
      return
      end