GNU bug report logs - #15320
[2.0.7] Rational number representation problem

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Package: guile;

Reported by: Josh Stokes <jsstokes2 <at> googlemail.com>

Date: Tue, 10 Sep 2013 15:45:02 UTC

Severity: normal

Done: Mark H Weaver <mhw <at> netris.org>

Bug is archived. No further changes may be made.

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Report forwarded to bug-guile <at> gnu.org:
bug#15320; Package guile. (Tue, 10 Sep 2013 15:45:02 GMT) Full text and rfc822 format available.
Acknowledgement sent to Josh Stokes <jsstokes2 <at> googlemail.com>:
New bug report received and forwarded. Copy sent to bug-guile <at> gnu.org. (Tue, 10 Sep 2013 15:45:03 GMT) Full text and rfc822 format available.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Josh Stokes <jsstokes2 <at> googlemail.com>
To: bug-guile <at> gnu.org
Subject: [2.0.7] Rational number representation problem
Date: Tue, 10 Sep 2013 14:28:37 +0100

[Message part 1 (text/plain, inline)]
It seems that certain small numbers are represented as integers, as (*
4294967296 4294967296) results in 0, but (* 3294967296 3294967296) returns
the correct value of 10856809481709551616. In addition, (ash 1 64) gives 0,
but (ash 1 65) works correctly.

[Message part 2 (text/html, inline)]
Reply sent to Mark H Weaver <mhw <at> netris.org>:
You have taken responsibility. (Thu, 12 Sep 2013 21:04:03 GMT) Full text and rfc822 format available.
Notification sent to Josh Stokes <jsstokes2 <at> googlemail.com>:
bug acknowledged by developer. (Thu, 12 Sep 2013 21:04:04 GMT) Full text and rfc822 format available.

Message #10 received at 15320-close <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Josh Stokes <jsstokes2 <at> googlemail.com>
Cc: 15320-close <at> debbugs.gnu.org
Subject: Re: bug#15320: [2.0.7] Rational number representation problem
Date: Thu, 12 Sep 2013 17:03:34 -0400

Josh Stokes <jsstokes2 <at> googlemail.com> writes:

> It seems that certain small numbers are represented as integers, as (*
> 4294967296 4294967296) results in 0, but (* 3294967296 3294967296)
> returns the correct value of 10856809481709551616. In addition, (ash 1
> 64) gives 0, but (ash 1 65) works correctly.

This is fixed in Guile 2.0.9.

In case you're curious: this bug came into existence when C compilers
started optimizing out overflow checks, on the theory that if a signed
integer overflow occurs then the behavior is unspecified and thus the
compiler can do whatever it likes.

http://stackoverflow.com/questions/14495636/strange-multiplication-behavior-in-guile-scheme-interpreter/14498437#14498437

    Thanks,
      Mark
bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Fri, 11 Oct 2013 11:24:03 GMT) Full text and rfc822 format available.
This bug report was last modified 11 years and 258 days ago.

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