From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22530 invoked by alias); 26 Sep 2006 21:22:41 -0000 Received: (qmail 22510 invoked by uid 48); 26 Sep 2006 21:22:34 -0000 Date: Tue, 26 Sep 2006 21:22:00 -0000 From: "sjmunroe at us dot ibm dot com" To: glibc-bugs@sources.redhat.com Message-ID: <20060926212234.3268.sjmunroe@us.ibm.com> Reply-To: sourceware-bugzilla@sourceware.org Subject: [Bug math/3268] New: fma for soft-fp is not correct. X-Bugzilla-Reason: CC Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org X-SW-Source: 2006-09/txt/msg00111.txt.bz2 List-Id: The current ./math/s_fma[fl].c implementation simply implements: double __fma (double x, double y, double z) { return (x * y) + z; } Which does mot meet the requirement of 754r "fused multiply-add: The operation fma(x,y,z) computes (x ×y )+z as if with unbounded range and precision, rounding only once to the destination format; see subclause 5.1." This implies (for example) that for double that the 106 bit result of the multiply be passed unrounded to the add (53 bit) and then final result found to 53 bits. -- Summary: fma for soft-fp is not correct. Product: glibc Version: 2.4 Status: NEW Severity: normal Priority: P2 Component: math AssignedTo: aj at suse dot de ReportedBy: sjmunroe at us dot ibm dot com CC: glibc-bugs at sources dot redhat dot com http://sourceware.org/bugzilla/show_bug.cgi?id=3268 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is.