GNU bug report logs - #11913
Unusual Emacs 24.1 arithmetic error (abs) on i386 machine

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Package: emacs;

Reported by: Rob Browning <rlb <at> defaultvalue.org>

Date: Wed, 11 Jul 2012 18:00:02 UTC

Severity: important

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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From: Rob Browning <rlb <at> defaultvalue.org>
To: Glenn Morris <rgm <at> gnu.org>
Cc: 11913 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>
Subject: bug#11913: Unusual Emacs 24.1 arithmetic error (abs) on i386 machine
Date: Sat, 14 Jul 2012 16:45:33 -0500

Glenn Morris <rgm <at> gnu.org> writes:

> But why does (abs 8.0) return an arithmetic error at all...?

OK, at the moment, I believe the short answer is because fabs() is
changing errno which triggers the default clause in IN_FLOAT() here:

    default: arith_error (float_error_fn_name, float_error_arg);

I've been told that this should be considered an Emacs bug because the
effect of fabs() on errno is strictly undefined, and so fabs() is within
its rights to do whatever it wants to the value.

Hope this helps.
-- 
Rob Browning
rlb @defaultvalue.org and @debian.org
GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
This bug report was last modified 12 years and 307 days ago.

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