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 15:07:05 -0700 Organization: UCLA Computer Science Department Message-ID: <5070AB89.4090900@cs.ucla.edu> References: <87y5jk3f7d.fsf@gmail.com> 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 1349561247 5731 80.91.229.3 (6 Oct 2012 22:07:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 6 Oct 2012 22:07:27 +0000 (UTC) Cc: jay.p.belanger@gmail.com, Edward Reingold , 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 00:07:32 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 1TKcWv-0002W7-Og for ged-emacs-devel@m.gmane.org; Sun, 07 Oct 2012 00:07:29 +0200 Original-Received: from localhost ([::1]:53222 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TKcWo-0005OY-VH for ged-emacs-devel@m.gmane.org; Sat, 06 Oct 2012 18:07:22 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:51952) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TKcWm-0005OI-GD for emacs-devel@gnu.org; Sat, 06 Oct 2012 18:07:21 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TKcWl-0003Zr-DY for emacs-devel@gnu.org; Sat, 06 Oct 2012 18:07:20 -0400 Original-Received: from smtp.cs.ucla.edu ([131.179.128.62]:38065) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TKcWl-0003ZF-5N; Sat, 06 Oct 2012 18:07:19 -0400 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp.cs.ucla.edu (Postfix) with ESMTP id 7AFB039E800D; Sat, 6 Oct 2012 15:07:10 -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 FDTrpnmMDyEN; Sat, 6 Oct 2012 15:07:09 -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 B19DC39E8007; Sat, 6 Oct 2012 15:07:09 -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:154145 Archived-At: On 10/06/2012 08:41 AM, Richard Stallman wrote: > Nobody used the Gregorian calendar in 1400, > so displaying dates from that year in Gregorian is an anachronism. It's OK and common to use an anachronism. It is standard practice to use modern calendars when talking about old dates. Almost nobody who writes about ancient history specifies dates in the calendars that were used at the time. Instead, people typically use a more-modern calendar, and write things like "Caesar was assassinated in 44 BC" or "Wu became emperor of all China in 280". It's true that it's also common practice to use the Julian calendar when talking about events that occurred before 1752 in British-contolled territory, and to use the Gregorian calendar for later events in that territory. But this is a special case, and it does not generalize well elsewhere. > Perhaps a calendar program should allow the user to specify changeover > date, offering convenient options for the main jurisdictions of interest. Unfortunately there are thousands of jurisdictions, and there is no systematic database of this stuff that I know of. Some places switched back and forth several times, and the switchover dates are not always known. In some locations, both calendars were used simultaneously, and whether you used Julian or Gregorian dates depended on what reason you wanted the dates. (A few places *still* use Julian for some official purposes.) And things get even more complicated once one considers all the other calendars that are or have been in practical use. So I'm afraid this suggestion, though appealing in principle, is not practical.