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* [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result @ 2011-10-17 8:39 kreckel at ginac dot de 2011-10-29 20:17 ` [Bug math/13305] " kreckel at ginac dot de ` (6 more replies) 0 siblings, 7 replies; 8+ messages in thread From: kreckel at ginac dot de @ 2011-10-17 8:39 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 Bug #: 13305 Summary: cacosh(+/-0.5+0.0*i) returns wrong result Product: glibc Version: 2.14 Status: NEW Severity: normal Priority: P2 Component: math AssignedTo: aj@suse.de ReportedBy: kreckel@ginac.de Classification: Unclassified Created attachment 6007 --> http://sourceware.org/bugzilla/attachment.cgi?id=6007 patch The current implementation computes cacosh(0.5+0.0*o)=0.0-1.047*i and cacosh(-0.5+0.0*i)=0.0-2.094*i. But that result has the wrong sign. Wes Loewer's patch for BZ#2182 was wrongly applied and should be reverted. The patch tried to fix the choice of branch cut by inverting res, if Re(res)<0.0. This is okay for picking the right branch cut but it suffers to the problem that round-off errors might have occurred in the computation of res. A safer approach is checking the position of the actual argument z. Indeed, the current implementation is doing just that a few lines above, but I don't see this in BZ#2182! Removing the extra test fixes the case. Impact: A different result is computed only when res, as computed so far, has a negative real part. But a negative real part of res can only happen due to round-off errors, as mathematically the argument of log is bounded below by +1.0. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de @ 2011-10-29 20:17 ` kreckel at ginac dot de 2011-11-19 22:19 ` kreckel at ginac dot de ` (5 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: kreckel at ginac dot de @ 2011-10-29 20:17 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 --- Comment #1 from Richard B. Kreckel <kreckel at ginac dot de> 2011-10-29 20:16:38 UTC --- I just see that in order to correctly account for signed zero, the patch has to be extended. After computing the square root, the condition if (__real__ x < 0.0) should be modified to if (signbit(x)). -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de 2011-10-29 20:17 ` [Bug math/13305] " kreckel at ginac dot de @ 2011-11-19 22:19 ` kreckel at ginac dot de 2011-11-19 22:21 ` kreckel at ginac dot de ` (4 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: kreckel at ginac dot de @ 2011-11-19 22:19 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 --- Comment #2 from Richard B. Kreckel <kreckel at ginac dot de> 2011-11-19 22:19:10 UTC --- I attach a cumulative patch. Please apply. Don't hesitate to contact me if anything is unclear. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de 2011-10-29 20:17 ` [Bug math/13305] " kreckel at ginac dot de 2011-11-19 22:19 ` kreckel at ginac dot de @ 2011-11-19 22:21 ` kreckel at ginac dot de 2011-12-19 9:37 ` aj at suse dot de ` (3 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: kreckel at ginac dot de @ 2011-11-19 22:21 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 --- Comment #3 from Richard B. Kreckel <kreckel at ginac dot de> 2011-11-19 22:20:38 UTC --- Created attachment 6066 --> http://sourceware.org/bugzilla/attachment.cgi?id=6066 cumulative patch -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de ` (2 preceding siblings ...) 2011-11-19 22:21 ` kreckel at ginac dot de @ 2011-12-19 9:37 ` aj at suse dot de 2011-12-22 2:03 ` drepper.fsp at gmail dot com ` (2 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: aj at suse dot de @ 2011-12-19 9:37 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 Andreas Jaeger <aj at suse dot de> changed: What |Removed |Added ---------------------------------------------------------------------------- AssignedTo|aj at suse dot de |drepper.fsp at gmail dot | |com -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de ` (3 preceding siblings ...) 2011-12-19 9:37 ` aj at suse dot de @ 2011-12-22 2:03 ` drepper.fsp at gmail dot com 2011-12-23 16:04 ` drepper.fsp at gmail dot com 2014-06-27 11:51 ` fweimer at redhat dot com 6 siblings, 0 replies; 8+ messages in thread From: drepper.fsp at gmail dot com @ 2011-12-22 2:03 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 Ulrich Drepper <drepper.fsp at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED --- Comment #4 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-12-22 02:02:43 UTC --- I've checked in the patch. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de ` (4 preceding siblings ...) 2011-12-22 2:03 ` drepper.fsp at gmail dot com @ 2011-12-23 16:04 ` drepper.fsp at gmail dot com 2014-06-27 11:51 ` fweimer at redhat dot com 6 siblings, 0 replies; 8+ messages in thread From: drepper.fsp at gmail dot com @ 2011-12-23 16:04 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=13305 Ulrich Drepper <drepper.fsp at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bert.barbe at oracle dot | |com --- Comment #5 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-12-23 16:02:28 UTC --- *** Bug 12786 has been marked as a duplicate of this bug. *** -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug math/13305] cacosh(+/-0.5+0.0*i) returns wrong result 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de ` (5 preceding siblings ...) 2011-12-23 16:04 ` drepper.fsp at gmail dot com @ 2014-06-27 11:51 ` fweimer at redhat dot com 6 siblings, 0 replies; 8+ messages in thread From: fweimer at redhat dot com @ 2014-06-27 11:51 UTC (permalink / raw) To: glibc-bugs https://sourceware.org/bugzilla/show_bug.cgi?id=13305 Florian Weimer <fweimer at redhat dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Flags| |security- -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-06-27 11:51 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-10-17 8:39 [Bug math/13305] New: cacosh(+/-0.5+0.0*i) returns wrong result kreckel at ginac dot de 2011-10-29 20:17 ` [Bug math/13305] " kreckel at ginac dot de 2011-11-19 22:19 ` kreckel at ginac dot de 2011-11-19 22:21 ` kreckel at ginac dot de 2011-12-19 9:37 ` aj at suse dot de 2011-12-22 2:03 ` drepper.fsp at gmail dot com 2011-12-23 16:04 ` drepper.fsp at gmail dot com 2014-06-27 11:51 ` fweimer at redhat dot com
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