Date: Thu, 5 Jul 2001 09:44:18 +0300 (IDT) From: Eli Zaretskii X-Sender: eliz AT is To: djgpp AT delorie DOT com Subject: Re: DJGPP reserves wrong int size In-Reply-To: <3b4372cf.92024930@news.primus.ca> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Reply-To: djgpp AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: djgpp AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On Wed, 4 Jul 2001, Graaagh the Mighty wrote: > >In any decent course in numerical computation, the first lesson > >teaches you that you cannot even solve a quadratic equation without > >risking numerical pitfalls. > > Newton's method? That does division, iteratively. The quadratic > formula? I doubt you'll have trouble with numerical instability except > right on the threshold of zero. It's enough to have two solutions close to one another to get into trouble, because the formula for solving the quadratic subtracts two numbers under the square root, and one of them is squared, so it loses half of its significant digits. > Now please stop spouting your "numerical wisdom" and give some real, > usable information about what might cause what was observed I did give usable information. If you don't want to hear any advice you don't like, don't post questions.