From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: =?UTF-8?Q?Aur=C3=A9lien_Aptel?= Newsgroups: gmane.emacs.help Subject: Re: why are there [v e c t o r s] in Lisp? Date: Sat, 17 Oct 2015 03:11:23 +0200 Message-ID: References: <87oafzpqfj.fsf@debian.uxu> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1445044320 21794 80.91.229.3 (17 Oct 2015 01:12:00 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 17 Oct 2015 01:12:00 +0000 (UTC) To: "help-gnu-emacs@gnu.org" Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sat Oct 17 03:11:56 2015 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 1ZnG2N-0007Bb-0A for geh-help-gnu-emacs@m.gmane.org; Sat, 17 Oct 2015 03:11:55 +0200 Original-Received: from localhost ([::1]:56524 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnG2M-0002Ii-Cp for geh-help-gnu-emacs@m.gmane.org; Fri, 16 Oct 2015 21:11:54 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:38160) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnG28-0002HI-Ss for help-gnu-emacs@gnu.org; Fri, 16 Oct 2015 21:11:41 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZnG1s-0004yO-Ka for help-gnu-emacs@gnu.org; Fri, 16 Oct 2015 21:11:25 -0400 Original-Received: from mail-lb0-x22d.google.com ([2a00:1450:4010:c04::22d]:34486) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnG1s-0004xJ-DZ for help-gnu-emacs@gnu.org; Fri, 16 Oct 2015 21:11:24 -0400 Original-Received: by lbbwb3 with SMTP id wb3so49565451lbb.1 for ; Fri, 16 Oct 2015 18:11:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:content-type; bh=eLy/NVnz8jqEJe26jgguBCNY3BvkHpwOCNuOgYN+TTQ=; b=bI4p9UUbuZySaVlzmK29IwJ1uzwe4Hvd7rcVvFHQcHcb0GTq8XVgxePooIiwXOlH45 DZbvaba6xSAF9W3Vn1axvotzlYO7cVk8dhvpO9eQXlBHhzapp+kZPxQCmUj0/7uwFMtO FHNAXhBbAMO0B/Gw/CbBUo4ejLqf17QvlMtQycZKnQhb47K+ba8oyAu81EMZPSNW2pqZ KA5NgCo+l6NCLpBGr+gWUDWh/kTohjiV/w5TNBZZqdiRl3uxZeO7aWcLFHG9rORNrv1Q GHooPleGQbGdeMF48YjgbZntPZD89IC5HyPDIrNJrV1pSCc87BmGW98/XYOj0C8P/VFl y5MQ== X-Received: by 10.112.64.72 with SMTP id m8mr9379297lbs.41.1445044283296; Fri, 16 Oct 2015 18:11:23 -0700 (PDT) Original-Received: by 10.112.167.73 with HTTP; Fri, 16 Oct 2015 18:11:23 -0700 (PDT) In-Reply-To: <87oafzpqfj.fsf@debian.uxu> X-Google-Sender-Auth: 9dS87gK9060AKKybsRK2yY6Vny4 X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:4010:c04::22d 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:107685 Archived-At: I'm just nitpicking, but: On Fri, Oct 16, 2015 at 3:12 AM, Emanuel Berg wrote: > direction and magnitude (in particular, it doesn't > have a position). But whatever the math, isn't that (a The direction and the position you're talking about are geometry concepts. Linear algebra is just a tool that can be used to model many things e.g. in mechanics to represent forces, in euclidian geometry to represent positions *or* directions, you can even used them to model text documents [1] etc. In pure linear algebra, "direction" and "position" are not defined for vectors. You could argue that elisp is using vectors to model a specific concept (constant time random access objects) and as such deserves its own notation, different from the list. See? It's all a matter of perspective. 1: https://en.wikipedia.org/wiki/Vector_space_model