Ian Jackson <ian@chiark.chu.cam.ac.uk>
to debian-bugs-request@pixar.com.
Full text available.
From WI.LeidenUniv.NL!jdassen Tue Oct 24 01:12:27 1995
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From: jdassen@WI.LeidenUniv.NL (J.H.M.Dassen)
Organization: Leiden University,
Dept. of Mathematics & Computer Science,
The Netherlands
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Subject: Re: Bug#1732: Bad arithmetic in new perl packages
To: lwall@scalpel.netlabs.com, perl5-porters@nicoh.com
Date: Tue, 24 Oct 1995 09:11:12 +0100 (MET)
Cc: debian-bugs@pixar.com
In-Reply-To: <9510231849.AA09797@scalpel.netlabs.com> from "Larry Wall" at Oct 23, 95 11:49:00 am
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> : > Perl seems to be confused making some arithmetic operations (additions).
> : > Sometimes the result of $a+=$b, when $a is 0 and $b is 2 happens to be
> : > 2.000004192 or something similar.
> :
> : Fernando, I unfortunately have no idea what is causing this. Please
> : provide a short script which shows this behaviour (reliably if possible).
> :
> : Perl5-porters, is this a known bug?
>
> No. Another possibility is that the compiler is using single-precision
> instead of double-precision floats. I think you get about 7 digits of
> accuracy in single precision.
Larry, I've forwarded Fernando's script to perl5-porters.
The perl5 package was compiled using Debian's gcc package (gcc 2.6.3)
in a.out binary format using '-O2 -fomit-frame-pointer' optimization;
the libc is Linux libc-4.6.27.
The output differs in the 10th decimal. The weird thing is that it
appears when copying the value.
I cannot reproduce the bug on the following configurations:
FreeBSD 2.1.0, perl 5.001m
SunOS 4.1.4, perl 5.000
HP-UX 9, perl 5.000
IRIX 5.3, perl 5.000
perl5-porters, please try to reproduce this
- on an non-linux system (with 5.001m)
- on a linux system (with a non-debian 5.001m)
- on a debian linux system under ELF (my home-machine is not net.connected).
Regards,
Ray
--
LEADERSHIP A form of self-preservation exhibited by people with auto-
destructive imaginations in order to ensure that when it comes to the crunch
it'll be someone else's bones which go crack and not their own.
- The Hipcrime Vocab by Chad C. Mulligan
jdassen@WI.LeidenUniv.NL (J.H.M.Dassen):debian-devel@pixar.com:Bug#1732.
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From math.ohio-state.edu!ilya Tue Oct 24 01:09:57 1995
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From: Ilya Zakharevich <ilya@math.ohio-state.edu>
Message-Id: <199510240809.EAA26616@monk.mps.ohio-state.edu>
Subject: Re: Bug#1732: Bad arithmetic in new perl packages (fwd)
To: jdassen@WI.LeidenUniv.NL (J.H.M.Dassen)
Date: Tue, 24 Oct 1995 04:09:13 -0400 (EDT)
Cc: perl5-porters@africa.nicoh.com, debian-bugs@pixar.com
In-Reply-To: <199510240745.HAA28263@ind206aa.wi.leidenuniv.nl> from "J.H.M.Dassen" at Oct 24, 95 08:45:17 am
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J.H.M.Dassen writes:
> ------------------------------------------------------------
> #!/usr/bin/perl
>
> @array=(
> "item1 4 units",
> "item2 1.5 units",
> "item3 8 units + see item2"
> );
>
> foreach (@array) {
> if( ($item_name,$amount,$unit,$delimiter,$moreinfo)=
> /^(\w+)\s*([\d\.]+)\s*(\w+)\s*(\+|$)\s*(.*)/) {
> $total+=$amount;
> }
> }
>
> $Total=$total;
> print "total=$total\n";
> print "Total=$Total\n";
> -----------------------------------------------------------------
>
> Output from perl-5.001-5:
> total=13.5
> Total=13.5000000003576
>
> Output from perl-5.001-3:
> total=13.5
> Total=13.5000000005364
>
No problem here, OS/2, 486/66x2 (1.5 years old).
It would help if you report the version of perl (perl -v) (there is no
such guy as 5.001-5), OS, compiler. Run myconfig.
Ilya
Ilya Zakharevich <ilya@math.ohio-state.edu>:debian-devel@pixar.com:Bug#1732.
Full text available.
From WI.LeidenUniv.NL!jdassen Tue Oct 24 00:45:51 1995
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From: jdassen@WI.LeidenUniv.NL (J.H.M.Dassen)
Organization: Leiden University,
Dept. of Mathematics & Computer Science,
The Netherlands
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Subject: Re: Bug#1732: Bad arithmetic in new perl packages (fwd)
To: perl5-porters@nicoh.com, debian-bugs@pixar.com
Date: Tue, 24 Oct 1995 08:45:17 +0100 (MET)
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Forwarded message:
>From alegre@mars.superlink.net Mon Oct 23 17:47:44 1995
Date: Mon, 23 Oct 1995 12:47:22 -0400 (EDT)
From: Fernando <alegre@mars.superlink.net>
To: "J.H.M.Dassen" <jdassen@WI.LeidenUniv.NL>
Subject: Re: Bug#1732: Bad arithmetic in new perl packages
In-Reply-To: <199510221657.QAA21984@ind143a.wi.leidenuniv.nl>
Message-ID: <Pine.SGI.3.91.951023124508.27119A-100000@mars.superlink.net>
MIME-Version: 1.0
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While trying to isolate the bug in perl-5.001-5 I managed to reproduce it
also with perl-5.001-3, although the output is not exactly the same.
I have tried the script below in two machines (a 386SX and a 486DX) with
the same result. It seems to be some conversion problem. It happens more
often in perl-5.001m because I noticed when I upgraded and my scripts
started to fail.
This is the test script:
------------------------------------------------------------
#!/usr/bin/perl
@array=(
"item1 4 units",
"item2 1.5 units",
"item3 8 units + see item2"
);
foreach (@array) {
if( ($item_name,$amount,$unit,$delimiter,$moreinfo)=
/^(\w+)\s*([\d\.]+)\s*(\w+)\s*(\+|$)\s*(.*)/) {
$total+=$amount;
}
}
$Total=$total;
print "total=$total\n";
print "Total=$Total\n";
-----------------------------------------------------------------
Output from perl-5.001-5:
total=13.5
Total=13.5000000003576
Output from perl-5.001-3:
total=13.5
Total=13.5000000005364
Thanks,
Fernando.
--
J.H.M. Dassen | RUMOUR Believe all you hear. Your world may
jDassen@wi.LeidenUniv.Nl | not be a better one than the one the blocks
Dassen@stpc.wi.LeidenUniv.Nl | live in but it'll be a sight more vivid.
| - The Hipcrime Vocab by Chad C. Mulligan
jdassen@WI.LeidenUniv.NL (J.H.M.Dassen):debian-devel@pixar.com:Bug#1732.
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From scalpel.netlabs.com!lwall Mon Oct 23 11:55:07 1995
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To: jdassen@WI.LeidenUniv.NL (J.H.M.Dassen)
Cc: alegre@mars.superlink.net, debian-bugs@pixar.com,
perl5-porters@africa.nicoh.com
Subject: Re: Bug#1732: Bad arithmetic in new perl packages
In-Reply-To: Your message of "Sun, 22 Oct 95 17:57:31 BST."
<199510221657.QAA21984@ind143a.wi.leidenuniv.nl>
Date: Mon, 23 Oct 95 11:49:00 -0700
From: Larry Wall <lwall@scalpel.netlabs.com>
: Fernando wrote to debian-bugs:
: > Pakckage: perl
: > Version: 5.001-5
: (perl5-porters, this is 5.001m without additional packages).
:
: > Notes: tried a.out only, happens also with 5.001-4, however 5.001-3 is OK
: (5.001-3 == 5.001e).
:
: > Perl seems to be confused making some arithmetic operations (additions).
: > Sometimes the result of $a+=$b, when $a is 0 and $b is 2 happens to be
: > 2.000004192 or something similar.
:
: Fernando, I unfortunately have no idea what is causing this. Please
: provide a short script which shows this behaviour (reliably if possible).
:
: Perl5-porters, is this a known bug?
No. Another possibility is that the compiler is using single-precision
instead of double-precision floats. I think you get about 7 digits of
accuracy in single precision.
Larry
Larry Wall <lwall@scalpel.netlabs.com>:debian-devel@pixar.com:Bug#1732.
Full text available.
From lafcol.lafayette.edu!doughera Sun Oct 22 12:44:57 1995
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From: Andy Dougherty <doughera@lafcol.lafayette.edu>
Sender: Andy Dougherty <doughera@lafcol.lafayette.edu>
Reply-To: Andy Dougherty <doughera@lafcol.lafayette.edu>
Subject: Re: Bug#1732: Bad arithmetic in new perl packages
To: "J.H.M.Dassen" <jdassen@WI.LeidenUniv.NL>
Cc: alegre@mars.superlink.net, debian-bugs@pixar.com,
perl5-porters@africa.nicoh.com
In-Reply-To: <199510221657.QAA21984@ind143a.wi.leidenuniv.nl>
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On Sun, 22 Oct 1995, J.H.M.Dassen wrote:
> Fernando wrote to debian-bugs:
(problem with 5.001m, but not 5.001e)
> > Perl seems to be confused making some arithmetic operations (additions).
> > Sometimes the result of $a+=$b, when $a is 0 and $b is 2 happens to be
> > 2.000004192 or something similar.
Without seeing a short example script, it's dangerous to guess, but I'll do
so anyway.
There is a very subtle bug that can arise in some rare situations where
perl has to convert back and forth between string and floating point
representations, but that's almost certainly not the problem here.
I also can't think of anything in 5.001m (as opposed to 5.001e) that
might have affected this.
I'd guess one of two things is going on:
1. This is the usual sort of problem that arises when folks forget
that floating point arithmetic isn't exact. Perl5 is pretty forgiving,
and tries hard to print what you want, but doesn't always succeed.
2. The tests are running on a buggy pentium :-).
> Fernando, I unfortunately have no idea what is causing this. Please
> provide a short script which shows this behaviour (reliably if possible).
Andy Dougherty doughera@lafcol.lafayette.edu
Dept. of Physics
Lafayette College, Easton PA 18042
Andy Dougherty <doughera@lafcol.lafayette.edu>:debian-devel@pixar.com:Bug#1732.
Full text available.
From WI.LeidenUniv.NL!jdassen Sun Oct 22 10:05:52 1995
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From: jdassen@WI.LeidenUniv.NL (J.H.M.Dassen)
Organization: Leiden University,
Dept. of Mathematics & Computer Science,
The Netherlands
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Subject: Re: Bug#1732: Bad arithmetic in new perl packages
To: alegre@mars.superlink.net, debian-bugs@pixar.com, perl5-porters@nicoh.com
Date: Sun, 22 Oct 1995 17:57:31 +0100 (MET)
In-Reply-To: <Pine.SGI.3.91.951022123527.19473A-100000@mars.superlink.net> from "Fernando" at Oct 22, 95 12:40:47 pm
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Fernando wrote to debian-bugs:
> Pakckage: perl
> Version: 5.001-5
(perl5-porters, this is 5.001m without additional packages).
> Notes: tried a.out only, happens also with 5.001-4, however 5.001-3 is OK
(5.001-3 == 5.001e).
> Perl seems to be confused making some arithmetic operations (additions).
> Sometimes the result of $a+=$b, when $a is 0 and $b is 2 happens to be
> 2.000004192 or something similar.
Fernando, I unfortunately have no idea what is causing this. Please
provide a short script which shows this behaviour (reliably if possible).
Perl5-porters, is this a known bug?
Ray
--
PATRIOTISM A great British writer once said that if he had to choose
between betraying his country and betraying a friend he hoped he would
have the decency to betray his country.
- The Hipcrime Vocab by Chad C. Mulligan
jdassen@WI.LeidenUniv.NL (J.H.M.Dassen):debian-devel@pixar.com:Bug#1732.
Full text available.From mars.superlink.net!alegre Sun Oct 22 09:37:26 1995 Return-Path: <alegre@mars.superlink.net> Received: from pixar.com by mongo.pixar.com with smtp (Smail3.1.28.1 #15) id m0t73Oo-0006PjC; Sun, 22 Oct 95 09:37 PDT Received: from jupiter.superlink.net by pixar.com with SMTP id AA26129 (5.67b/IDA-1.5 for debian-bugs-pipe@mongo.pixar.com); Sun, 22 Oct 1995 09:36:59 -0700 Received: from earth.superlink.net (earth.superlink.net [204.97.220.6]) by jupiter.superlink.net (8.6.12/8.6.12) with ESMTP id MAA10007 for <@jupiter.superlink.net:debian-bugs@pixar.com>; Sun, 22 Oct 1995 12:36:53 -0400 Received: from mars.superlink.net by earth.superlink.net via ESMTP (950215.SGI.8.6.10/940406.SGI.AUTO) for <@jupiter.superlink.net:debian-bugs@pixar.com> id MAA06871; Sun, 22 Oct 1995 12:58:27 -0400 Received: by mars.superlink.net (950511.SGI.8.6.12.PATCH526/940406.SGI) id MAA19702; Sun, 22 Oct 1995 12:40:48 -0400 Date: Sun, 22 Oct 1995 12:40:47 -0400 (EDT) From: Fernando <alegre@mars.superlink.net> To: debian-bugs@pixar.com Subject: Bad arithmetic in new perl packages Message-Id: <Pine.SGI.3.91.951022123527.19473A-100000@mars.superlink.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Pakckage: perl Version: 5.001-5 Notes: tried a.out only, happens also with 5.001-4, however 5.001-3 is OK Perl seems to be confused making some arithmetic operations (additions). Sometimes the result of $a+=$b, when $a is 0 and $b is 2 happens to be 2.000004192 or something similar.
Fernando <alegre@mars.superlink.net>:
Your message didn't have a Package: line at the start (in the pseudo-header following the real mail header), or didn't have a psuedo-header at all.
This makes it much harder for us to categorise and deal with your problem report; please ensure that you say which package(s) and version(s) the problem is with next time. Some time in the future the problem reports system may start rejecting such messages.
Full text available.
debian-devel@pixar.com:Bug#1732.
Full text available.