From owner-cvs-all@FreeBSD.ORG Wed Mar 2 14:37:46 2005 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EAC5916A4CF; Wed, 2 Mar 2005 14:37:46 +0000 (GMT) Received: from mailout01.sul.t-online.com (mailout01.sul.t-online.com [194.25.134.80]) by mx1.FreeBSD.org (Postfix) with ESMTP id 76A8843D55; Wed, 2 Mar 2005 14:37:46 +0000 (GMT) (envelope-from Alexander@Leidinger.net) Received: from fwd23.aul.t-online.de by mailout01.sul.t-online.com with smtp id 1D6Uyv-0005fW-00; Wed, 02 Mar 2005 15:37:45 +0100 Received: from Andro-Beta.Leidinger.net (XGTdCwZ-8ezXwvZxodufAsRXAGQi20+rsdpMXkQAb2wlnItlf2V0U1@[217.83.27.180]) by fwd23.sul.t-online.de with esmtp id 1D6UyV-2KahQe0; Wed, 2 Mar 2005 15:37:19 +0100 Received: from localhost (localhost [127.0.0.1])j22EaSdQ086136; Wed, 2 Mar 2005 15:36:29 +0100 (CET) (envelope-from Alexander@Leidinger.net) Received: from 141.113.101.32 ([141.113.101.32]) by netchild.homeip.net (Horde) with HTTP for ; Wed, 2 Mar 2005 15:36:28 +0100 Message-ID: <20050302153628.xf36f2rgyss0sk04@netchild.homeip.net> X-Priority: 3 (Normal) Date: Wed, 2 Mar 2005 15:36:28 +0100 From: Alexander Leidinger To: David Schultz References: <200502240632.j1O6WDP9029589@repoman.freebsd.org> <20050226023149.GA63314@VARK.MIT.EDU> In-Reply-To: <20050226023149.GA63314@VARK.MIT.EDU> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: 7bit User-Agent: Internet Messaging Program (IMP) H3 (4.0.2) / FreeBSD-4.11 X-ID: XGTdCwZ-8ezXwvZxodufAsRXAGQi20+rsdpMXkQAb2wlnItlf2V0U1@t-dialin.net X-TOI-MSGID: b1125226-648a-4839-a8da-9cdfbffa8aff cc: cvs-src@freebsd.org cc: src-committers@freebsd.org cc: imp@freebsd.org cc: cvs-all@freebsd.org Subject: Re: cvs commit: src/lib/msun/src e_expf.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Mar 2005 14:37:47 -0000 David Schultz wrote: > This is related to a good reason why we can't switch the default > precision on i386 to extended. Many of the functions in libm use > minimax approximations, which are ``optimal'' approximations in > the sense that their maximum error over all in-range inputs is the > smallest possible (unless more terms are used). These approximations > take rounding error into account, so when the machine precision is > increased, they're no longer optimal and the error in the approximation > can increase significantly. There are less efficient methods that > don't depend on the exact machine precision, e.g. Chebyshev > approximations, but it would be a PITA to switch everything. What's the problem with recomputing the minimax approximations for extended precision? Is there no tool available to compute them so it is more work than you are willing/able to do ATM? Or is it the amount of computing time needed to recompute the approximations? Bye, Alexander. -- http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137 softy n. [IBM] Hardware hackers' term for a software expert who is largely ignorant of the mysteries of hardware.