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From: "jsm28 at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/16620] New: [ldbl-128ibm] exp10l spurious overflows / bad directed rounding results
Date: Fri, 21 Feb 2014 02:19:00 -0000 [thread overview]
Message-ID: <bug-16620-131@http.sourceware.org/bugzilla/> (raw)
https://sourceware.org/bugzilla/show_bug.cgi?id=16620
Bug ID: 16620
Summary: [ldbl-128ibm] exp10l spurious overflows / bad directed
rounding results
Product: glibc
Version: 2.19
Status: NEW
Severity: normal
Priority: P2
Component: math
Assignee: unassigned at sourceware dot org
Reporter: jsm28 at gcc dot gnu.org
Host: powerpc*-*-linux*
The ldbl-128ibm implementation of exp10l uses a version of log(10) split into
high and low parts - but the low part is negative, so probably causing spurious
overflows from __ieee754_expl (exp_high) in cases close to the overflow
threshold (and definitely, given libgcc fixed for directed rounding modes,
results below LDBL_MAX for overflow when rounding downward / to zero just above
that threshold, which is the case where I found this problem). The split
log(10) needs to be such that both parts are positive to avoid this issue.
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next reply other threads:[~2014-02-21 2:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-21 2:19 jsm28 at gcc dot gnu.org [this message]
2014-06-13 8:10 ` [Bug math/16620] " fweimer at redhat dot com
2015-09-30 23:36 ` cvs-commit at gcc dot gnu.org
2015-09-30 23:37 ` jsm28 at gcc dot gnu.org
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