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Re: [testsuite gfortran] partial fix for secnds*.f
- From: Tim Prince <tprince at myrealbox dot com>
- To: Dominique Dhumieres <dominiq at lps dot ens dot fr>
- Cc: gcc-patches at gcc dot gnu dot org, fortran at gcc dot gnu dot org
- Date: Mon, 28 May 2007 14:01:10 -0700
- Subject: Re: [testsuite gfortran] partial fix for secnds*.f
- References: <20070528181820.2DDE15BB6C@mailhost.lps.ens.fr>
- Reply-to: tprince at computer dot org
Dominique Dhumieres wrote:
However... as a general rule, I've learned that it is better to add real
values from small to big (less loss of precision that way).
What I have learned too, but apparently this is a trick for fortran
dinosaurs!-)
Not at all, what was known in ancient times has been confirmed
repeatedly. Ignoring this rule, while it sometimes could be done safely
in extra precision x87 code, compounded the confusion encountered by
those who didn't care to pay attention. Now, it is more important than
ever to avoid sloppy code which gives different results according to
precision of intermediate evaluation.