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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!news.maxwell.syr.edu!pumpkin.pangea.ca!news.mira.net.au!news.netspace.net.au!news.mel.connect.com.au!news.syd.connect.com.au!news.bri.connect.com.au!corolla.OntheNet.com.au!not-for-mail From: Tony Griffiths <tonyg@OntheNet.com.au> Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: FreeBSD 221 math problem, help Date: Fri, 30 May 1997 15:05:36 +1000 Organization: On the Net (ISP on the Gold Coast, Australia) Lines: 29 Message-ID: <338E6020.5045@OntheNet.com.au> References: <01bc6afa$0dd23720$3976c9ce@amuancw110> Reply-To: tonyg@OntheNet.com.au NNTP-Posting-Host: swanee.nt.com.au Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 3.0 (WinNT; I) To: Tim Brown <Tim.Brown@ctg.com> Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:41852 Tim Brown wrote: > > I am getting a math error (FPE) in some pretty old code. The code works > basically everywhere but freebsd 221. It even seems to work on older > freebsd systems. > > The code is: > > -216 + 5 -1316 *40 / (40 * -.00012120) > > I have broken it down like so to narrow it down: > > double x = -217 +5 -1316 *40; > double y= 40 * -.00012120; > double a = x/y; > > I ran this and when I got the FPE while in gdb, y was 0. Why?? > It seems that "y" was rounded off to 0. All other OS's I have run this on > (AIX, SunOS, older freeBSD, others) do not have this problem. Is there a > magical gcc command line option I need to use? You're not using a Pentium with the FP bug by any chance? Is there a program on the net for testing if you have a "dud" Pentium? The problem was in multiplication (I think)! If so please post a pointer... Tony