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From: "jsm28 at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sources.redhat.com
Subject: [Bug math/13629] clog() returns wrong values around z=1
Date: Sat, 03 Mar 2012 21:28:00 -0000 [thread overview]
Message-ID: <bug-13629-131-KYX4a7nvB0@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-13629-131@http.sourceware.org/bugzilla/>
http://sourceware.org/bugzilla/show_bug.cgi?id=13629
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|aj at suse dot de |unassigned at sourceware
| |dot org
--- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-03-03 21:26:56 UTC ---
Confirmed in current source code by inspection. The implementation approach of
log(hypot) for finding the real part of clog will cause undue overflows for
large input, inaccurate results from undue underflow for subnormal input, and
inaccurate results for z close to |z|=1 (not just close to 1 itself). The
general case of z close to that circle will be more complicated to fix than the
overflow and underflow cases.
clog10 (a GNU extension, name reserved in ISO C) has the same issues.
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next prev parent reply other threads:[~2012-03-03 21:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 14:12 [Bug math/13629] New: " fxcoudert at gcc dot gnu.org
2012-01-27 15:57 ` [Bug math/13629] " tprince at computer dot org
2012-01-27 15:58 ` tprince at computer dot org
2012-01-27 16:00 ` tprince at computer dot org
2012-03-03 21:28 ` jsm28 at gcc dot gnu.org [this message]
2012-03-20 0:39 ` jsm28 at gcc dot gnu.org
2012-07-26 11:36 ` jsm28 at gcc dot gnu.org
2012-07-31 14:26 ` jsm28 at gcc dot gnu.org
2012-09-25 19:49 ` jsm28 at gcc dot gnu.org
2014-06-27 10:03 ` fweimer at redhat dot com
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