C     This program reads in a list of real numbers.  The number of
C     values entered is determined by the first value (assumed to be an
C     integer) which the user enters.  The program reports the average
C     of the negative values, the average of the non-negatives values,
C     the minimum and maximum values, as well as the place in the list
C     where the minimum and maximum values occurred (i.e., the index for
C     these entries).
C
C     John Schneider
C     CptS 203, HW 4, problem 3
C--------------------------------------------------------------------------
      program avgdat
      implicit none

C.....
C     min    = minimum value
C     max    = maximum value
C     sumneg = sum of the negative values
C     sumpos = sum of the non-negative values
C     x      = used to hold the current entry
C
C     i      = dummy loop variable
C     n      = the number of values to be entered
C     cntneg = count of the negative values
C     cntpos = count of the non-negative values
C     minpos = index for the minimum value
C     maxpos = index for the maximum value
C.....
      
      real min, max, x, sumpos, sumneg
      integer i, n, cntpos, cntneg, maxpos, minpos

      print *, 'Enter the number of values.'
      read *, n

C.....Read in first value and initialize variables.      
      read *, x
      min = x
      max = x
      sumneg = 0.0
      sumpos = 0.0
      maxpos = 1
      minpos = 1

C.....
C     Check if value is negative or not.  If negative, add to sumneg and
C     initialize cntneg and cntpos to 1 and 0, respectively.  Otherwise
C     add value to sumpos and initialize cntneg and cntpos to 0 and 1,
C     respectively. 
C.....      
      if (x .ge. 0.0) then
         sumpos = sumpos + x
         cntneg = 0
         cntpos = 1
      else
         sumneg = sumneg + x
         cntneg = 1
         cntpos = 0
      endif


C.....Loop over the rest of the data.
      do i=2,n
         read *, x
         if (x .ge. 0.0) then
            sumpos = sumpos + x
            cntpos = cntpos + 1
         else
            sumneg = sumneg + x
            cntneg = cntneg + 1
         endif

C........
C        Check if value is less then current minimum or greater than
C        current maximum.  If so, reset min or max appropriately and
C        update index position holder.
C........
         if (x .lt. min) then
            min = x
            minpos = i
         elseif (x .gt. max) then
            max = x
            maxpos = i
         endif

      enddo

C.....Print out averages, checking that counts are not zero.      
      if (cntneg .eq. 0) then
         print *, 'There were no negative values.'
      else
         print *, 'Average of negative numbers: ', sumneg/cntneg
      endif

      if (cntpos .eq. 0) then
         print *, 'There were no non-negative values.'
      else
         print *, 'Average of non-negative numbers: ', sumpos/cntpos
      endif

      print *, 'Average of all numbers: ',
     &     (sumneg+sumpos)/(cntneg+cntpos)

      print *, 'Minimum = ',min,': It was element ',minpos, ' in list.'
      print *, 'Maximum = ',max,': It was element ',maxpos, ' in list.'

      stop
      end