Article View: comp.arch
Article #12102IEEE arithmetic
From: jbs
Date: Sat, 15 Jun 1991 01:25
Date: Sat, 15 Jun 1991 01:25
19 lines
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1364 bytes
David Seal (quoting someone quoting the fortran standard):
>The missing rule is (ANSI X3.9-1978 sect 6.6):
> "Any numeric operation whose result is not mathematically defined is
> prohibited in the execution of an executable program. Examples are
> dividing by zero and raising a zero-valued primary to a zero-valued or
> negative-valued power."
>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.
Some comments:
1. The result of multiplying 2 reals is always mathematically de-
fined. Therefore I don't see how this clause prohibits multiplies which
will overflow or underflow.
2. Ordinary IEEE numbers don't really correspond to single mathema-
tical real numbers, they correspond to intervals. Inf and -inf are just
the names of the intervals on the ends.
James B. Shearer
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!ucbvax!WATSON.IBM.COM!jbs From: jbs@WATSON.IBM.COM Newsgroups: comp.arch Subject: IEEE arithmetic Message-ID: <9106150144.AA14442@ucbvax.Berkeley.EDU> Date: 15 Jun 91 01:25:14 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 19