From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#58929: 29.0.50; Calc: finding roots utpn doesn't work as advertised Date: Thu, 03 Nov 2022 11:13:46 +0200 Message-ID: <83a6588kol.fsf@gnu.org> References: <8773828B-3A5F-4B15-8786-91F6FCB6D2E2@acm.org> <87k04es5bt.fsf@rfc20.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="31996"; mail-complaints-to="usenet@ciao.gmane.io" Cc: matt@rfc20.org, 58929@debbugs.gnu.org To: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu Nov 03 10:15:24 2022 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oqWJm-00082G-Oc for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 03 Nov 2022 10:15:22 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oqWJV-0002PL-Vb; Thu, 03 Nov 2022 05:15:06 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oqWJS-0002N5-7w for bug-gnu-emacs@gnu.org; Thu, 03 Nov 2022 05:15:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1oqWJR-0000t4-V9 for bug-gnu-emacs@gnu.org; Thu, 03 Nov 2022 05:15:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1oqWJR-0000gf-QQ for bug-gnu-emacs@gnu.org; Thu, 03 Nov 2022 05:15:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 03 Nov 2022 09:15:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 58929 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 58929-submit@debbugs.gnu.org id=B58929.16674668442526 (code B ref 58929); Thu, 03 Nov 2022 09:15:01 +0000 Original-Received: (at 58929) by debbugs.gnu.org; 3 Nov 2022 09:14:04 +0000 Original-Received: from localhost ([127.0.0.1]:47971 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1oqWIW-0000eg-6N for submit@debbugs.gnu.org; Thu, 03 Nov 2022 05:14:04 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:48190) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1oqWIU-0000e5-0j for 58929@debbugs.gnu.org; Thu, 03 Nov 2022 05:14:02 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oqWIO-0000kM-Dp; Thu, 03 Nov 2022 05:13:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=MIME-version:References:Subject:In-Reply-To:To:From: Date; bh=HmRX4UTcU6ZyhHcPxK4Ovk7boOJ74vw5QpUFOdXI+RY=; b=JuyfATZgfWr9FtF572k/ ihoJP5otF6LO5ZFJbbVvEn2zBIGQWLh35TKDpBugYZ6h1raAJOZat5mM7v4GSM6nCKhyMSE4J5z9i GxfWscxDe8dZsIzwrzuy1zhnPpEgwiZx7WY0UfAnFJFuzak+WW6JPY0QRB7h/imKqJMRXC6mX2s92 APznLosKFuF0R+z1TiiUh8yl7Qa/cTsmn5qaE2G73itFjFUwTuCKAAntVHczvyisUFptITlIdcSSP EMpdYJijitR/oRhOdYRkKAijoC72xaRVoKT3qu0TB7Zx3mTyl69jawpZPS8X3h7IaWc0t1XQIT49f 6tYqbBs2c0wOHg==; Original-Received: from [87.69.77.57] (helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oqWIN-0004me-Ln; Thu, 03 Nov 2022 05:13:56 -0400 In-Reply-To: (message from Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= on Thu, 3 Nov 2022 09:53:02 +0100) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: "bug-gnu-emacs" Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.bugs:246937 Archived-At: > Cc: 58929@debbugs.gnu.org > From: Mattias Engdegård > Date: Thu, 3 Nov 2022 09:53:02 +0100 > > Of course an actual numerical analyst would know immediately what to do. Is there one in the audience? I have good experience from using this technique: https://www.researchgate.net/publication/226830173_On_the_Structure_of_Zero_Finders It employs a hybrid method that doesn't need derivatives (but is almost as fast as Newton). However, its main advantage (which is a huge one in some real-life situations) is that the structure of the algorithm allows the caller to make arbitrary modifications to the approximations that the algorithm produces, and in general have complete control on the iterations' process. In particular, one can easily deal with situations where the root approximation goes out of the expected range, or lands in the area where the function doesn't behave well enough.