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Xref: sserve comp.unix.bsd:3241 comp.bugs.4bsd:1870 Path: sserve!manuel!munnari.oz.au!spool.mu.edu!uwm.edu!wupost!cs.utexas.edu!lgc.com!lgc.com!danson From: danson@lgc.com (Doug Anson) Newsgroups: comp.unix.bsd,comp.bugs.4bsd Subject: Re: 'ps aux' floating exception bug (386BSD) Message-ID: <1992Aug7.154037.977@lgc.com> Date: 7 Aug 92 15:40:37 GMT Article-I.D.: lgc.1992Aug7.154037.977 References: <1992Aug7.125733.16779@agora.uucp> Sender: usenet@lgc.com Organization: LandMark Graphics Corporation LGC Lines: 68 Nntp-Posting-Host: voodoo.lgc.com In article <1992Aug7.125733.16779@agora.uucp>, davidg@agora.rain.com (David Greenman) writes: |> After a suggestion from Arne Henrik Juul <arnej@lise.unit.no>, I |> decided to replace the stock libm.a with the 386 assembly version |> that I ported from mach back when I was using 0.0. The problem with |> 'ps aux' "Floating Point Exception" is now gone. |> I still don't know why the exception is reported so late when |> using gdb, nor do I understand why the problem was intermittent. I |> suspect that there is a bug somewhere in the kernel with the handling |> of the FPU. |> I ran 'paranoia' with the supplied libm.a; here is what it |> uncovered: |> |> ... |> Testing powers Z^i for small Integers Z and i. |> DEFECT: computing |> (2.00000000000000000e+00) ^ (3.00000000000000000e+00) |> yielded 7.99999999999281997e+00; |> which compared unequal to correct 8.00000000000000000e+00 ; |> they differ by -7.18003434485581238e-12 . |> Errors like this may invalidate financial calculations |> involving interest rates. |> Similar discrepancies have occurred 121 times. |> |> ... |> |> Testing X^((X + 1) / (X - 1)) vs. exp(2) = 7.38905609893065218e+00 as X -> 1. |> Accuracy seems adequate. |> Testing powers Z^Q at four nearly extreme values. |> DEFECT: computing |> (2.00000000000000000e+00) ^ (1.00700000000000000e+03) |> yielded 1.37153101719718930e+303; |> which compared unequal to correct 1.37153101719842530e+303 ; |> they differ by -1.23095497606496200e+291 . |> Similar discrepancies have occurred 4 times. |> |> ... |> These problems don't occur when 'paranoia' is linked with the assembly |> version of libm.a. While these two 'DEFECT's seem somewhat minor, they |> may very well be indicative of a more serious problem. |> I recall that someone else did a port of the GNU 386 libm.a a while |> back...is this conveniently available somewhere, or would it be |> prudent for me to make my port of this available? |> |> --- |> David Greenman |> davidg%implode@agora.rain.com |> Hi, I have encountered the same problems with ps(1). I have recently installed a 387-33 on my machine running 386BSD 0.1. I have successfully installed 0.1 and have the source on line. ps -aux gives Floating Exception when run. Is there a fix for this? How can I be sure 386BSD is really using my 387? Where can I get the above mentioned library? Thanks, Doug -- ------------------------------------------- Doug Anson Internet: danson@lgc.com Phone: 713-579-4739 SNAIL: Landmark Graphics Corporation LGC 333 Cypress Run Houston, TX 77094 -------------------------------------------