From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Thorsten Jolitz Newsgroups: gmane.emacs.help Subject: Re: distance from Easter Island to Chile Date: Sun, 20 Apr 2014 12:26:15 +0200 Message-ID: <874n1onvp4.fsf@gmail.com> References: <87mwfguasr.fsf@nl106-137-194.student.uu.se> <83mwfgfnl0.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1397989527 16737 80.91.229.3 (20 Apr 2014 10:25:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 20 Apr 2014 10:25:27 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sun Apr 20 12:25:21 2014 Return-path: Envelope-to: geh-help-gnu-emacs@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 1Wbow2-0004gG-5Q for geh-help-gnu-emacs@m.gmane.org; Sun, 20 Apr 2014 12:25:18 +0200 Original-Received: from localhost ([::1]:45033 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wbow1-0006es-PD for geh-help-gnu-emacs@m.gmane.org; Sun, 20 Apr 2014 06:25:17 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:58035) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wbovk-0006aH-Gz for help-gnu-emacs@gnu.org; Sun, 20 Apr 2014 06:25:05 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wbovf-0000wk-7S for help-gnu-emacs@gnu.org; Sun, 20 Apr 2014 06:25:00 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:34007) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wbovf-0000wc-18 for help-gnu-emacs@gnu.org; Sun, 20 Apr 2014 06:24:55 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Wbove-0004Bf-0U for help-gnu-emacs@gnu.org; Sun, 20 Apr 2014 12:24:54 +0200 Original-Received: from e178190125.adsl.alicedsl.de ([85.178.190.125]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 20 Apr 2014 12:24:54 +0200 Original-Received: from tjolitz by e178190125.adsl.alicedsl.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 20 Apr 2014 12:24:54 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 39 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: e178190125.adsl.alicedsl.de User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Cancel-Lock: sha1:xdan4iAc9rH/9rDcaDFUQoXb+nI= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:97253 Archived-At: Eli Zaretskii writes: >> From: Barry Margolin >> Date: Sun, 20 Apr 2014 03:01:36 -0400 >> >> In article , >> Eli Zaretskii wrote: >> >> > This is inaccurate (Earth is not a sphere). >> >> How accurate does your input have to be for that to be a significant? >> I.e. if you're calculating the distance between two cities, and each >> city is 5 miles wide, the distance is +/- 10 miles depending on where in >> the two cities you decide to get the coordinates from. So if the error >> in the formula is 2 miles, it's less than the inaccuracy in the input, >> so the formula should be good enough. > > No one said that these calculations are only for distances between > large cities. > > Anyway, the error induced by assuming spherical Earth can be up to 1%, > which is not insignificant when the distances are on the order of > magnitude of many hundreds of kilometers (3757 km and 4301 km values > were cited by the OP). I think one of the two French guys who had the task to establish a world-wide accepted meter unit as ,------------------------------------------------------------------------- | 1/10,000,000 part of the quarter of a meridian, measurement (1795) by | Delambre and Mechain (http://en.wikipedia.org/wiki/History_of_the_metre) `------------------------------------------------------------------------- figured this out the hard way and became a depressed alcoholic because of an unexplainable 300m 'measurement-error' in his triangulations. -- cheers, Thorsten