[SUMMARY] f90: double precision constants

From: Gerhard Nolte <gnolte_at_gwdg.de>
Date: Tue, 16 Jun 1998 10:06:14 +0200

Dear Gurus,

I asked:

   on Digital Unix 4.0d the F90 compiler (DFABASE500) shows an unexpected
   behaviour: assigning a constant to a double precision variable is
   sensitive in respect to the d0-appendix (see small example
   program). f77 has the expected behaviour. Is it a bug or a feature of
   f90?

          8< ---------------- cut here -------------------- >8
      program Double_precision_test

C Gibt's einen Unterschied zwischen unter f90 zwischen den Konstanten
C mit und ohne d0 Appendix?

      double precision x, xd0

      x = 1.23456
      xd0 = 1.23456d0

      print*, ' x =', x
      print*, 'xd0 =', xd0

      print*, ' x-xd0 = ', x - xd0

      end
          8< ---------------- cut here -------------------- >8

The opinion of the majority was that a constant without d0-appendix isn't
of type double precision and hence has a different internal representation
than the same constant with d0 appendix. Therefore the behaviour of the f90
compiler is a feature.

Thanks to
Burch Seymour RTPS <bseymour_at_encore.com>
"Dr. Tom Blinn, 603-884-0646" <tpb_at_zk3.dec.com>
Jerome M Berkman <jerry_at_uclink.berkeley.edu>
Ian Mortimer <mortimer_at_physics.uq.edu.au>

Gerhard

-- 
Gerhard Nolte
Email: gnolte_at_gwdg.de   Voice: +49-551-5176-716  Fax: +49-551-5176-704
MPI fuer Stroemungsforschung, Bunsenstr. 10, 37073 Goettingen, Germany

Received on Tue Jun 16 1998 - 10:10:31 NZST