public inbox for glibc-bugs@sourceware.org help / color / mirror / Atom feed
From: "jsm28 at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sourceware.org Subject: [Bug math/15416] New: catan, catanh inaccuracy from atan2 Date: Mon, 29 Apr 2013 16:25:00 -0000 [thread overview] Message-ID: <bug-15416-131@http.sourceware.org/bugzilla/> (raw) http://sourceware.org/bugzilla/show_bug.cgi?id=15416 Bug #: 15416 Summary: catan, catanh inaccuracy from atan2 Product: glibc Version: 2.17 Status: NEW Severity: normal Priority: P2 Component: math AssignedTo: unassigned@sourceware.org ReportedBy: jsm28@gcc.gnu.org Classification: Unclassified When catan computes __real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den), the value of den may be inaccurate when close to 0, resulting in an inaccurate real part of the result when __real__ x is also small. For example, catan (0x1p-27 + 1.0i) gives a result with real part 0.785398163397448279 on x86_64, which is only accurate to 8 decimal places, about half the precision expected (the exact value is 0.785398165260093458846617868453411006955...). The same applies to catanh. -- 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.
next reply other threads:[~2013-04-29 16:25 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-04-29 16:25 jsm28 at gcc dot gnu.org [this message] 2013-04-30 11:30 ` [Bug math/15416] " jsm28 at gcc dot gnu.org 2014-06-13 18:10 ` fweimer at redhat dot com
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-15416-131@http.sourceware.org/bugzilla/ \ --to=sourceware-bugzilla@sourceware.org \ --cc=glibc-bugs@sourceware.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).