Newsgroups: comp.arch
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: IEEE arithmetic (Goldberg paper)
Message-ID: <1991Jun11.175639.22558@zoo.toronto.edu>
Date: Tue, 11 Jun 1991 17:56:39 GMT
References: <1991Jun7.204910.878@borland.com> <192@armltd.uucp>
Organization: U of Toronto Zoology

In article <192@armltd.uucp> dseal (David Seal) writes:
>>Who knows whether IEEE infinity is a "mathematically defined result"? If you
>
>I would think it isn't: it doesn't correspond to a single mathematical real
>number in the way that ordinary IEEE numbers do.

Why do you insist that the standard real numbers be the mathematical system
used?  Number systems which include infinities are neither novel nor somehow
illegitimate.  The real question about FORTRAN vs IEEE is how precise the
FORTRAN standard is about the nature of the number system it is running on.
Given that FP systems containing infinities are *not* new -- IEEE did not
invent this idea -- I would be surprised if a careful reading of the
standard mandated pure mathematical reals.

(The real answer, of course, is that the FORTRAN standard was too early
to even consider IEEE FP, and attempts to determine the interaction of the
two by reading between the lines are a bit silly.)
-- 
"We're thinking about upgrading from    | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 to SunOS 3.5."              |  henry@zoo.toronto.edu  utzoo!henry