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* [Bug math/14868] New: ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 @ 2012-11-21 23:34 jsm28 at gcc dot gnu.org 2012-11-22 15:03 ` [Bug math/14868] " jsm28 at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: jsm28 at gcc dot gnu.org @ 2012-11-21 23:34 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=14868 Bug #: 14868 Summary: ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 Product: glibc Version: 2.16 Status: NEW Severity: normal Priority: P2 Component: math AssignedTo: unassigned@sourceware.org ReportedBy: jsm28@gcc.gnu.org Classification: Unclassified Host: powerpc* The ldbl-128ibm implementation of hypotl returns a+b if the absolute values of the arguments have a ratio of over 2^60. But while in such a case it's true that the round-to-nearest result will be the larger absolute value of an argument, a+b isn't the correct way to compute that result, and results in large errors until the ratio is over 2^106. For example, hypotl (1.0L, 0x1p-61L) has a 17592186044416 ulp error (as computed using libm-test.inc). This appears to be what's causing 16 ulp errors for csqrtl tests as well. -- 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] 4+ messages in thread
* [Bug math/14868] ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 2012-11-21 23:34 [Bug math/14868] New: ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 jsm28 at gcc dot gnu.org @ 2012-11-22 15:03 ` jsm28 at gcc dot gnu.org 2014-06-14 11:04 ` fweimer at redhat dot com 2014-06-14 11:04 ` fweimer at redhat dot com 2 siblings, 0 replies; 4+ messages in thread From: jsm28 at gcc dot gnu.org @ 2012-11-22 15:03 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=14868 Joseph Myers <jsm28 at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED --- Comment #1 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-11-22 15:03:25 UTC --- Fixed for 2.17 by: commit 8e27e3cc453849158e069dbed0eea7b8113ab8ff Author: Joseph Myers <joseph@codesourcery.com> Date: Thu Nov 22 14:57:22 2012 +0000 Fix ldbl-128ibm hypotl inaccuracy for arguments with large ratio (bug 14868). -- 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] 4+ messages in thread
* [Bug math/14868] ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 2012-11-21 23:34 [Bug math/14868] New: ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 jsm28 at gcc dot gnu.org 2012-11-22 15:03 ` [Bug math/14868] " jsm28 at gcc dot gnu.org @ 2014-06-14 11:04 ` fweimer at redhat dot com 2014-06-14 11:04 ` fweimer at redhat dot com 2 siblings, 0 replies; 4+ messages in thread From: fweimer at redhat dot com @ 2014-06-14 11:04 UTC (permalink / raw) To: glibc-bugs https://sourceware.org/bugzilla/show_bug.cgi?id=14868 Florian Weimer <fweimer at redhat dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC|fweimer at redhat dot com | -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug math/14868] ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 2012-11-21 23:34 [Bug math/14868] New: ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 jsm28 at gcc dot gnu.org 2012-11-22 15:03 ` [Bug math/14868] " jsm28 at gcc dot gnu.org 2014-06-14 11:04 ` fweimer at redhat dot com @ 2014-06-14 11:04 ` fweimer at redhat dot com 2 siblings, 0 replies; 4+ messages in thread From: fweimer at redhat dot com @ 2014-06-14 11:04 UTC (permalink / raw) To: glibc-bugs https://sourceware.org/bugzilla/show_bug.cgi?id=14868 Florian Weimer <fweimer at redhat dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |fweimer at redhat dot com Flags| |security- -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-06-14 11:04 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-11-21 23:34 [Bug math/14868] New: ldbl-128ibm hypotl inaccurate for arguments differing by 2^60 jsm28 at gcc dot gnu.org 2012-11-22 15:03 ` [Bug math/14868] " jsm28 at gcc dot gnu.org 2014-06-14 11:04 ` fweimer at redhat dot com 2014-06-14 11:04 ` fweimer at redhat dot com
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