From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4342 invoked by alias); 31 May 2005 14:08:17 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 4023 invoked by uid 22791); 31 May 2005 14:07:59 -0000 Received: from ns2.suse.de (HELO mx2.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Tue, 31 May 2005 14:07:59 +0000 Received: from hermes.suse.de (hermes-ext.suse.de [195.135.221.8]) (using TLSv1 with cipher EDH-RSA-DES-CBC3-SHA (168/168 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id 8F6CF1D85A for ; Tue, 31 May 2005 16:07:57 +0200 (CEST) From: Andreas Schwab To: gcc@gcc.gnu.org Subject: Re: What is wrong with Bugzilla? [Was: Re: GCC and Floating-Point] References: <002d01c5643c$cfcc1140$bebc2997@bagio> <26669933.1117479096256.JavaMail.root@dtm1eusosrv72.dtm.ops.eu.uu.net> <429B7506.8010107@moene.indiv.nluug.nl> <20050531121701.GQ3541@ay.vinc17.org> <20050531124837.GT3541@ay.vinc17.org> <20050531134304.GV3541@ay.vinc17.org> X-Yow: I appoint you ambassador to Fantasy Island!!! Date: Tue, 31 May 2005 15:58:00 -0000 In-Reply-To: <20050531134304.GV3541@ay.vinc17.org> (Vincent Lefevre's message of "Tue, 31 May 2005 15:43:05 +0200") Message-ID: User-Agent: Gnus/5.110003 (No Gnus v0.3) Emacs/22.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-SW-Source: 2005-05/txt/msg01691.txt.bz2 Vincent Lefevre writes: > On 2005-05-31 15:33:48 +0200, Andreas Schwab wrote: >> Vincent Lefevre writes: >> > On 2005-05-31 14:27:01 +0200, Andreas Schwab wrote: >> >> Vincent Lefevre writes: >> >> > But as I said on my page, this isn't much a problem since users >> >> > who really need *extended* precision can still set the rounding >> >> > precision to extended precision; this isn't portable, but extended >> >> > precision isn't portable anyway. >> >> >> >> What about LDBL_* from ? >> > >> > What do you mean here? >> >> They give you access to long double in a portable manner, > > No, this is not portable, Sure they are, since they are required since C89. > since if extended precision is necessary to get correct results for some > application, the same application run on PowerPC, where there is no > extended precision, would give incorrect results. You can use to find that out. That's what portability is about. >> but if you change the rounding mode then the constants are no longer >> accurate. > > The implementation could provide another way to get the necessary > information; perhaps nextafterl()... But you still have to take care of (1.0 + LDBL_EPSILON) != 1.0, or the other required identities in . Andreas. -- Andreas Schwab, SuSE Labs, schwab@suse.de SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."