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.devel Subject: Re: hypotenuse Date: Sun, 21 Jul 2024 19:12:13 +0300 Message-ID: <86frs2bu76.fsf@gnu.org> References: <8734o9sdig.fsf@posteo.net> <87wmllqq66.fsf@posteo.net> <87plrdqnhc.fsf@posteo.net> <87le21qldj.fsf_-_@posteo.net> <878qy1at52.fsf@dataswamp.org> <87plr6u8al.fsf_-_@dataswamp.org> <86wmleby8w.fsf@gnu.org> <86sew2bxii.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="8514"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Max Nikulin Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Jul 21 18:12:59 2024 Return-path: Envelope-to: ged-emacs-devel@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 1sVZBD-000208-Ot for ged-emacs-devel@m.gmane-mx.org; Sun, 21 Jul 2024 18:12:59 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sVZAY-0002Yl-5m; Sun, 21 Jul 2024 12:12:18 -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 1sVZAW-0002YZ-MS for emacs-devel@gnu.org; Sun, 21 Jul 2024 12:12:16 -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 1sVZAW-0000Cr-Cp; Sun, 21 Jul 2024 12:12:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=iVEzKt1MmHlRMqkLK5/cOLfa0XLAt14HLr7K9rTRk4w=; b=f/G16rr0g5oW sQTVjAkWQEiaBwC0j6D1iAbhIy+ez+pJpQFTpaerVdxZhD6fI3aVAEUlftlJtl4AsOeKXhs33heJG tkC5NdZY39zk/HfNOQ9ZJgPooK5Hjfb0hQIj178Yf2AksH8mUxCBsG5SjYNlVI+6KRbUVW8TbtM29 beRjCjt/gOxljzIAFXJHgdHpX6k1Wl2q0eaD/r8zQwFpfFy1LpMwzqxQgKkLAQVkSR7A73i9X880I hrr4DAgWcD19v2bQw3DYpnxqcLNBydpuntcxs4i3Pi9RiUHNmSFnm3abWJQktgDqBbDwfoANJ/3ue EFBEMaSKCSFBen+CVnKHbA==; In-Reply-To: (message from Max Nikulin on Sun, 21 Jul 2024 22:54:53 +0700) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:321903 Archived-At: > From: Max Nikulin > Date: Sun, 21 Jul 2024 22:54:53 +0700 > > On 21/07/2024 22:12, Christopher Dimech wrote: > >>>> (defun hypotenuse (c1 c2) > >>>> (sqrt (+ (* c1 c1) (* c2 c2))) ) > > > > I have a solution to the problem in fortran, but not in elisp. I could > > include it. Its implementation required serious concentration. > > Underflow/overflow issues may be solved with a few lines of code and it > does matter if it is fortran, elisp, or another language (besides > pathological ones). The problem is to avoid error above 1 ULP. Right, overflow and underflow are just the tip of a very large iceberg. > In 2021 hypot implementation in glibc was replaced by a more precise one: > https://sourceware.org/git/?p=glibc.git;a=commit;h=6c848d70383e1dbe932ef41723ac0abfdeec7ca8 Which is exactly why I said we should use the existing implementation in the standard library.