program main
c This program calculates the variance of the first 10**9 integers
c using only one cpu on the Macintosh.
c To compile with the Absoft Fortran compiler, use:
c f77 -O -Q92 uni.f -o uni.out
      implicit none
      integer TickCount
      external TickCount
      integer NINT
      parameter(NINT=1000000000)
      integer n, start_program, end_program
      double precision make_ssq, sum, mean, ssq
      n = NINT
      sum = 0.0d0
      start_program = TickCount()

c calculate sum
      ssq = make_ssq(n)
c calculate sum of squares
      call make_sum(n,sum)
      mean = sum/n
      write (*,'(i15,1x,f20.3,1x,f21.3)') n, mean, (ssq/n)-(mean * mean)

      end_program = TickCount()
      write (*,*)
      write (*,'("time in sec: ",f7.2)') (end_program-start_program)/60.
      write (*,*) 'hit carriage return to quit'
      pause
      stop
      end

      double precision function make_ssq(n)
      integer n
      double precision s
      integer i
      s = 0.0d0
      do 10 i = 0, n-1
      s = s + dble(i)*i
   10 continue
      make_ssq = s
      return
      end

      subroutine make_sum(n,s)
      integer n
      double precision s
      integer i
      do 10 i = 0, n-1
      s = s + dble(i)
   10 continue
      return
      end