From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20026 invoked by alias); 3 Feb 2012 15:09:53 -0000 Received: (qmail 19998 invoked by uid 22791); 3 Feb 2012 15:09:52 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO sourceware.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 03 Feb 2012 15:09:39 +0000 From: "vincent-srcware at vinc17 dot net" To: glibc-bugs@sources.redhat.com Subject: [Bug math/13658] sincos() is incorrect for large inputs on x86_64 Date: Fri, 03 Feb 2012 15:09:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: math X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: vincent-srcware at vinc17 dot net X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: drepper.fsp at gmail dot com X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org X-SW-Source: 2012-02/txt/msg00011.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=3D13658 --- Comment #2 from Vincent Lef=C3=A8vre 2012-02-03 15:09:07 UTC --- For the reference about the hardware trig instructions, you can see "Intel= =C2=AE 64 and IA-32 Architectures Software Developer's Manual Volume 1: Basic Architecture" on: =20 http://www.intel.com/content/www/us/en/processors/architectures-software-de= veloper-manuals.html in particular Section 8.1.3.2, which says: "The FPTAN, FSIN, FCOS, and FSINCOS instructions set the C2 flag to 1 to indicate that the source operand is beyond the allowable range of =C2=B12^6= 3 and clear the C2 flag if the source operand is within the allowable range." So, outside the interval [-2^63,+2^63] ("allowable range"), these instructi= ons must not be used (or they can be used, but with a fallback if the C2 flag is set to 1). But note that the glibc implementation is more accurate, even wi= th (very probably) correct rounding, so that it is better to use it anyway. --=20 Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=3Demail ------- You are receiving this mail because: ------- You are on the CC list for the bug.