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Date:      Sat, 11 Oct 1997 02:29:31 +0000 (GMT)
From:      Terry Lambert <tlambert@primenet.com>
To:        rcarter@consys.com (Russell L. Carter)
Cc:        gjohnson@nola.srrc.usda.gov, tlambert@primenet.com, freebsd-hackers@FreeBSD.ORG
Subject:   Re: Floating point exceptions
Message-ID:  <199710110229.TAA11733@usr02.primenet.com>
In-Reply-To: <199710110146.SAA08283@dnstoo.consys.com> from "Russell L. Carter" at Oct 10, 97 06:46:05 pm

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> |Fix:		Correct the code to not generate exceptions
> 
> Hmm, I don't think so.  There are a variety of reasons that NA people
> want to use those carefully thought out exceptions.  Find
> 'em yerself.  

Well, in Physics we used them in a linear congruential random number
generator to get the same pseudo-random values each time for pair
production calculations.  The errors were all overflows.

When we did this, we set the mask immediately before, and unset it
immediately afterwards.  We did this so we could tell the difference
between an exception that was on purpose and one that indicated a bug.

Of course, you might not be interested in distinguishing these cases,
but I'm sure your calculations will suffer if you don't.  ;-).


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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