From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31492 invoked by alias); 29 Apr 2013 13:51:53 -0000 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 Received: (qmail 31432 invoked by uid 48); 29 Apr 2013 13:51:51 -0000 From: "bugdal at aerifal dot cx" To: glibc-bugs@sourceware.org Subject: [Bug math/14412] Removal of sysdeps/x86_64/fpu/s_sincos.S causes regressions Date: Mon, 29 Apr 2013 13:51:00 -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: enhancement X-Bugzilla-Who: bugdal at aerifal dot cx X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: 2.18 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" MIME-Version: 1.0 X-SW-Source: 2013-04/txt/msg00222.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=14412 --- Comment #37 from Rich Felker 2013-04-29 13:51:50 UTC --- At the outer edges of that range, the error is "only" around 1000 ulps. This isn't correct, but at least it's better than just having 4 or 5 bits of precision (or none at all). Since the x87 internally uses a 66-bit representation of pi, and doubles are 52-bit, I suspect precision starts to trail off around 16384*pi, but it will be bad even for much smaller values when the result is close to zero. Experimentally, 0x1p18 seems to be the first power of two for which the result is wrong within 15 decimal places, but 0x1p14*M_PI is already badly wrong (only the first 4 decimal places are correct). -- 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.