This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: Fix x86/x86_64 expl/exp10l spurious underflows (bug 16348)
- From: Andreas Jaeger <aj at suse dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>, libc-alpha at sourceware dot org
- Date: Thu, 27 Mar 2014 19:30:39 +0100
- Subject: Re: Fix x86/x86_64 expl/exp10l spurious underflows (bug 16348)
- Authentication-results: sourceware.org; auth=none
- References: <Pine dot LNX dot 4 dot 64 dot 1403271650430 dot 649 at digraph dot polyomino dot org dot uk>
On 03/27/2014 05:51 PM, Joseph S. Myers wrote:
> This patch fixes bug 16348, spurious underflows from x86/x86_64 expl
> on arguments close to 0. These implementations effectively use expm1
> (on the fractional part of the argument) internally, so resulting in
> spurious underflows when the result is very close to 1. For arguments
> small enough that the round-to-nearest correct result is 1, this patch
> uses 1+x instead.
>
> These implementations are also used for exp10l and so the patch fixes
> similar issues there (the 0x1p-67 threshold being small enough to be
> correct for exp10l as well as expl). But because of spurious
> underflows in other exp10 implementations (bug 16560), the tests
> aren't added for exp10 at this point - they can be added when the
> other exp10 parts of that bug are fixed.
Thanks,
Andreas
--
Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg)
GPG fingerprint = 93A3 365E CE47 B889 DF7F FED1 389A 563C C272 A126