From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/12693 Path: news.gmane.org!.POSTED!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: catan errors Date: Tue, 10 Apr 2018 16:32:06 -0400 Message-ID: <20180410203206.GJ3094@brightrain.aerifal.cx> References: <20180410195007.GI3094@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: blaine.gmane.org 1523392217 2786 195.159.176.226 (10 Apr 2018 20:30:17 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 10 Apr 2018 20:30:17 +0000 (UTC) User-Agent: Mutt/1.5.21 (2010-09-15) To: musl@lists.openwall.com Original-X-From: musl-return-12709-gllmg-musl=m.gmane.org@lists.openwall.com Tue Apr 10 22:30:11 2018 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1f5zu7-0000f3-44 for gllmg-musl@m.gmane.org; Tue, 10 Apr 2018 22:30:11 +0200 Original-Received: (qmail 11627 invoked by uid 550); 10 Apr 2018 20:32:18 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 11601 invoked from network); 10 Apr 2018 20:32:17 -0000 Content-Disposition: inline In-Reply-To: Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:12693 Archived-At: On Tue, Apr 10, 2018 at 05:23:12PM -0300, dgutson . wrote: > On Tue, Apr 10, 2018 at 4:50 PM, Rich Felker wrote: > > > The OpenBSD catan implementation we're using has a number of > > nonsensical "overflow" (goto ovrf) conditions that aren't errors, > > reported by mepholic on irc. I think the attached patch fixes them > > without introducing new problems, but I'm not sure if any other > > problems remain. > > > > Note that, of the three cases removed: > > > > 1. Is not an exceptional case at all, and made no sense to begin with. > > > > 2. Is only exceptional if x and a are both zero; atan(2x,0) is > > perfectly well-defined. > > > > 3. Is only possible if y==1.0 and x==0.0, which is the only real > > exceptional case for atan: z==I. > > > > > Besides the trigonometric case, are you considering de-normalized numbers, > such as 4.94066e-324 as divisor? > For example: > double x = 1.0; > double y = 5E-324; > x / y is inf, and y != 0.0. > Shouldn't 'a' be checked against that number or its absolute value >= > minimum? Can you clarify where you think something goes wrong? Rich