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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!news.wildstar.net!news.ececs.uc.edu!newsfeeds.sol.net!europa.clark.net!ais.net!news.idt.net!oksennus.binary.net!news.mid.net!news.cjnetworks.com!usenet From: nospam@here Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: FreeBSD 221 math problem, help Date: 31 May 1997 07:52:39 GMT Organization: Capital Journal Networks Lines: 45 Distribution: world Message-ID: <5molc7$nns@topeka.cjnetworks.com> References: <01bc6afa$0dd23720$3976c9ce@amuancw110> <338E6020.5045@OntheNet.com.au> NNTP-Posting-Host: port209.cjnetworks.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Newsreader: <QVT/News ver. 4.0> Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:41916 In article <338E6020.5045@OntheNet.com.au>, Tony Griffiths <tonyg@OntheNet.com.au> writes: >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... Terje Mathieson (sp?), an x86 assembly language guru in Norway wrote a nice little assembler routine for testing for the FDIV bug back when it was first announced. I have a copy, but it's locked away in an ancient backup of WFW 3.11 that I'm not gonna restore for anybody. The original poster would have to have a fairly old Pentium to be affected by this. My thought on this is that the poster probably needs to compile in hardware FP support. BTW, I think that assembler routine was p87test.com (possibly in a .zip file with other things like a readme and the source), which archie should find without too much difficulty. -------------- Troy Smith (tdsmith at cjnetworks dot com) I hate having to use spamfoil measures.