program dblecons
c
c   Look at difference between use of single and double precision
c   constants
c
c   John Mahaffy  11/20/96
c
      integer r8
      parameter (r8=selected_real_kind(13,100))
      real (r8)  y1, y2, y3
c
c  on most machines, the above is the same as
c     double precision y1, y2, y3
c
      y1 = 2.1e0
      y2 = 2.1d0
      y3 = 2.1_r8
      print *, 'For "y1=2.1" we get a value in y1 of ',y1
      print *, 'For "y2=2.1d0" we get a value in y2 of ',y2
      print *, '  Setting r8=selected_real_kind(13,100), then'
      print *, 'For "y3=2.1_r8" we get a value in y3 of ',y3
c
c   Every Compiler that I have used results in different printed
c   values for y1 and y2 in the last 7 or 8 digits.  y2 and y3
c   should be the same.
c
      end