From owner-freebsd-hackers Fri Oct 10 19:29:51 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id TAA24835 for hackers-outgoing; Fri, 10 Oct 1997 19:29:51 -0700 (PDT) (envelope-from owner-freebsd-hackers) Received: from usr02.primenet.com (tlambert@usr02.primenet.com [206.165.6.202]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id TAA24827 for ; Fri, 10 Oct 1997 19:29:49 -0700 (PDT) (envelope-from tlambert@usr02.primenet.com) Received: (from tlambert@localhost) by usr02.primenet.com (8.8.5/8.8.5) id TAA11733; Fri, 10 Oct 1997 19:29:32 -0700 (MST) From: Terry Lambert Message-Id: <199710110229.TAA11733@usr02.primenet.com> Subject: Re: Floating point exceptions To: rcarter@consys.com (Russell L. Carter) Date: Sat, 11 Oct 1997 02:29:31 +0000 (GMT) Cc: gjohnson@nola.srrc.usda.gov, tlambert@primenet.com, freebsd-hackers@FreeBSD.ORG In-Reply-To: <199710110146.SAA08283@dnstoo.consys.com> from "Russell L. Carter" at Oct 10, 97 06:46:05 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > |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.