Path: utzoo!attcan!uunet!lll-winken!ames!ncar!tank!uxc!uxc.cso.uiuc.edu!uxg.cso.uiuc.edu!uxe.cso.uiuc.edu!mcdonald
From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.lang.fortran
Subject: Re: CFT/CFT77 gotcha
Message-ID: <50500101@uxe.cso.uiuc.edu>
Date: 23 Jan 89 15:07:00 GMT
References: <23252@beta.lanl.gov>
Lines: 15
Nf-ID: #R:beta.lanl.gov:23252:uxe.cso.uiuc.edu:50500101:000:769
Nf-From: uxe.cso.uiuc.edu!mcdonald    Jan 23 09:07:00 1989



>Bug or feature?  I suppose you would have to say "feature", but really it is
>an example of the fact that you should not make assumptions about the properties
>of floating point arithmetic.

That latter clause is a true statement, no doubt about it. But,
nevertheless, there is an IEEE standard for floating point formats
and operations. It is extremely specific about what a given result
must be, and reasonably close to the "principle of least astonishment".
Most of the computers in the world get quite close to this standard -
for in range results they seem to be EXACTLY according to it.
I think it would behoove Cray (and that other big computer manufacturer
with the leading up to three zeros in the mantissa) to convert to
it (at least for in-range results).