From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg via Users list for the GNU Emacs text editor Newsgroups: gmane.emacs.help Subject: Re: Floating Point computations in elisp Date: Sun, 20 Dec 2020 01:45:08 +0100 Message-ID: <87ft41b90r.fsf@zoho.eu> References: <87mtybyrd1.fsf@zoho.eu> Reply-To: Emanuel Berg Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="1271"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:HYclUMQ5yLisqECWka4/421KDfY= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sun Dec 20 02:02:36 2020 Return-path: Envelope-to: geh-help-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 1kqn7M-0000CX-5W for geh-help-gnu-emacs@m.gmane-mx.org; Sun, 20 Dec 2020 02:02:36 +0100 Original-Received: from localhost ([::1]:39914 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kqn7L-0007Pr-8F for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 19 Dec 2020 20:02:35 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:60116) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kqn3t-0005aF-CA for help-gnu-emacs@gnu.org; Sat, 19 Dec 2020 19:59:01 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:55438) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kqn3m-0003dN-Rp for help-gnu-emacs@gnu.org; Sat, 19 Dec 2020 19:58:56 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kqmvB-0006jC-N5 for help-gnu-emacs@gnu.org; Sun, 20 Dec 2020 01:50:01 +0100 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:126587 Archived-At: Jean Louis wrote: > * Emanuel Berg via Users list for the GNU Emacs text editor > [2020-12-18 20:09]: > >> (defun compute-space-distance (dist num-beams beam-width) >> (let*((spaces (1+ num-beams)) >> (dist-covered (* num-beams beam-width)) >> (dist-uncovered (- dist dist-covered)) >> (space (/ dist-uncovered spaces 1.0) )) >> space )) >> >> ;; (insert (format "\n;; %.2f" (compute-space-distance 262 16 12))) >> ;; 4.12 > > If I wish to arrive to Tau Ceti from Earth and it is maybe 11.8 light > years distant, how many years do I need to get there provided I trave > 5,000 km per hour? How about: 2 548 584 years (defun tau-ceti (speed) (let*((dist (* 11.8 9.46 (expt 10 12))) (time (/ dist speed) ) (days (/ time 24)) (whole-days (round days)) ) (format-seconds "%y years" (- (float-time (encode-time 0 0 0 whole-days 0 0)) (float-time (encode-time 0 0 0 0 0 0)) )))) ;; (tau-ceti 5000) -- underground experts united http://user.it.uu.se/~embe8573 https://dataswamp.org/~incal