From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: The Emacs Calculator and calendar Date: Sat, 06 Oct 2012 23:22:51 -0700 Organization: UCLA Computer Science Department Message-ID: <50711FBB.1040507@cs.ucla.edu> References: <87y5jk3f7d.fsf@gmail.com> <5070AB89.4090900@cs.ucla.edu> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1349590978 26217 80.91.229.3 (7 Oct 2012 06:22:58 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 7 Oct 2012 06:22:58 +0000 (UTC) Cc: jay.p.belanger@gmail.com, reingold@iit.edu, emacs-devel@gnu.org To: rms@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Oct 07 08:23:04 2012 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TKkGR-0000jG-Ty for ged-emacs-devel@m.gmane.org; Sun, 07 Oct 2012 08:23:00 +0200 Original-Received: from localhost ([::1]:36529 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TKkGM-0004Bt-0l for ged-emacs-devel@m.gmane.org; Sun, 07 Oct 2012 02:22:54 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:60992) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TKkGJ-0004Bo-Cv for emacs-devel@gnu.org; Sun, 07 Oct 2012 02:22:52 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TKkGI-0002KZ-BR for emacs-devel@gnu.org; Sun, 07 Oct 2012 02:22:51 -0400 Original-Received: from smtp.cs.ucla.edu ([131.179.128.62]:49313) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TKkGI-0002KV-2n; Sun, 07 Oct 2012 02:22:50 -0400 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp.cs.ucla.edu (Postfix) with ESMTP id 60496A60002; Sat, 6 Oct 2012 23:22:49 -0700 (PDT) X-Virus-Scanned: amavisd-new at smtp.cs.ucla.edu Original-Received: from smtp.cs.ucla.edu ([127.0.0.1]) by localhost (smtp.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id RpDdaGRK6gxf; Sat, 6 Oct 2012 23:22:48 -0700 (PDT) Original-Received: from [192.168.1.3] (pool-108-23-119-2.lsanca.fios.verizon.net [108.23.119.2]) by smtp.cs.ucla.edu (Postfix) with ESMTPSA id B05E6A60001; Sat, 6 Oct 2012 23:22:48 -0700 (PDT) User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 131.179.128.62 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:154154 Archived-At: On 10/06/2012 08:49 PM, Richard Stallman wrote: > all of Europe used the Julian calendar for hundreds of years. Unfortunately that's not correct, if by "Julian calendar" one means the Julian calendar that Emacs implements. (In this email I'll call it the "Emacs Julian calendar", to clearly distinguish it from the many other Julian calendars.) For example, England never used the Emacs Julian calendar: before 1752, English years started on March 25, and after 1752 England used Gregorian. The Holy Roman Empire used the Emacs Julian calendar for only four decades, from 1544 to 1582. Other European countries used the Emacs Julian calendar for a bit longer in some cases, but off the top of my head I can think of only one country that actually used the Emacs Julian calendar for hundreds of years, namely Russia from 1700 through 1918. > Jan 5, 1000 in the Gregorian calendar was Dec 31, 999 > in the Julian calendar. It's true that nobody called it "Jan 5, 1000" back then, because the Gregorian calendar wasn't invented yet. But it's also true that very few people called it "December 31, 999" back then, because the Emacs-style Julian calendar was pretty rare, perhaps even nonexistent, back then. So both calendars are being used proleptically (i.e., extrapolating them backward into the past) if we are talking about that date. > If something happened in Europe on that day, which year > do modern historians say it occurred in? Most modern European historians would probably say 999. But for the date 30 days later, some would say 999, others 1000, and still others 999/1000. Old dates are a real mess. This may help to explain why Ed Reingold worded his advice so strongly. The method of Unix cal and Emacs calc looks cute, but it's incorrect in the sense that it doesn't correspond to any actual historical practice, so it arguably causes more harm (by confusing users) than it cures. The method of Emacs calendar is much saner.