220 19171 article Path: news.gmane.org!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Point class Date: Wed, 22 Jul 2015 14:53:52 -0400 Lines: 44 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1437591254 27977 80.91.229.3 (22 Jul 2015 18:54:14 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 22 Jul 2015 18:54:14 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC37LBFWUIFBBTGNX6WQKGQEHR4YHTA@isocpp.org Wed Jul 22 20:54:06 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f197.google.com ([209.85.217.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZHz9a-0005XD-Az for gclcip-std-proposals@m.gmane.org; Wed, 22 Jul 2015 20:54:06 +0200 Original-Received: by lbvb1 with SMTP id b1sf59977181lbv.3 for ; Wed, 22 Jul 2015 11:54:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:date:lines:message-id:references :mime-version:content-type:user-agent:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=H3PFVJiMySlfmepStd2e05Ld4K9mtztEji/zhVdCAYs=; b=RucywzcW18j2NFLCyvqlkRnYw1AbdIRf5pyg3P1nEWn8Th9dBe/jSK1wK0zPCQAg/k bR1cmyhUWCjH87p6ecyiRsg/sB5ZdnASc09alp8ZNRKWbstnC2Qaaehd+rg6aHF7+FoB +SJmM9e+tSqsWl6y4VBiUtDW7MaqC6mCS7z4hWMpqAw9PO5IjbEWfaJ9Z1HQGBSpUqjU FzyyupO7b9grIrSZmOMlnZuK6rXiZQZi69Ioi5XAOIStJZOdFNT2t0WbHZf6g56CZNW3 FevYp4BHpXVm6nxchzV14jQlM2M8/n0+bdkKyIFgukSwRbXzruH1sSQD9adhSa57aR5d X-Gm-Message-State: ALoCoQkcwIrIitoapS5LHm36bMVNbd6R6sl4Lzu/+npsvv3frGcxCHiv/tvSmyPFO1Xm4n5pQ6cd X-Received: by 10.194.184.6 with SMTP id eq6mr1844716wjc.4.1437591245647; Wed, 22 Jul 2015 11:54:05 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.205.6 with SMTP id lc6ls135384lac.80.gmail; Wed, 22 Jul 2015 11:54:03 -0700 (PDT) X-Received: by 10.112.139.131 with SMTP id qy3mr3773370lbb.4.1437591243908; Wed, 22 Jul 2015 11:54:03 -0700 (PDT) Original-Received: from plane.gmane.org (plane.gmane.org. [80.91.229.3]) by mx.google.com with ESMTPS id cz4si1914712lac.110.2015.07.22.11.54.03 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 22 Jul 2015 11:54:03 -0700 (PDT) Received-SPF: pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) client-ip=80.91.229.3; Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ZHz9W-0005VG-VY for std-proposals@isocpp.org; Wed, 22 Jul 2015 20:54:03 +0200 Original-Received: from tripoint.kitware.com ([66.194.253.20]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 22 Jul 2015 20:54:02 +0200 Original-Received: from mwoehlke.floss by tripoint.kitware.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 22 Jul 2015 20:54:02 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 35 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: tripoint.kitware.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 In-Reply-To: X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) smtp.mail=gclcip-std-proposals@m.gmane.org; dmarc=fail (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:19171 Archived-At: On 2015-07-22 14:40, David Haim wrote: > I'm sorry. but a point is not a vector. the standard must be mathematical > correct. > now, we might want to argue if to name it "vector" class or "point" class > (plus, I don't see how can we push another std::vector class :) standard > C++ does not have an other namespaces other than "std"). std::la::vector :-) ('la' being short for 'linear algebra'). Or 'std::algebra', or whatnot. > I still think that mathematically talking - the 3 fundamental definitions > are "Point" "Line" and "Plane". we need to stick to these definitions from > the bottom up if we want to add new mathematical/graphical objects to > standard C++. That list MUST include a vector type. Both a line and plane can be defined by vectors (direction or normal, respectively). So you either NEED a vector type distinct from a point type, or you need one class that can be used in either context. > you also didn't took into consideration that not all vectors start from the > origin. Only a minuscule fraction of users actually want "vectors" that have a defined origin. Everyone else only cares about magnitude and direction, which is the pure linear algebra definition. (Again, a "vector" in LA is a numeric tuple; *nothing more*.) In fact, I'll challenge you to name a use case for a "vector" that is defined as an magnitude, direction, AND origin. And that isn't actually a line segment, or a case where the "origin" and "vector" aren't actually separate concepts (e.g. position and velocity of a particle). -- Matthew -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. .