Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.mixmin.net!weretis.net!feeder1.news.weretis.net!newsfeed.CARNet.hr!news.spin.it!bofh.it!news.nic.it!robomod From: Geert Stappers Newsgroups: linux.debian.maint.java Subject: Re: GeoGebra - bug report Date: Mon, 24 Aug 2015 17:30:03 +0200 Message-ID: References: X-Original-To: Walter Lenzenweger X-Mailbox-Line: From debian-java-request@lists.debian.org Mon Aug 24 15:21:09 2015 Old-Return-Path: X-Amavis-Spam-Status: No, score=-3 tagged_above=-10000 required=5.3 tests=[BAYES_00=-2, RP_MATCHES_RCVD=-1] autolearn=no autolearn_force=no X-Policyd-Weight: using cached result; rate:hard: -6.1 X-Greylist: delayed 438 seconds by postgrey-1.35 at bendel; Mon, 24 Aug 2015 15:03:34 UTC MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.5.21 (2010-09-15) X-Mailing-List: archive/latest/18594 List-ID: List-URL: List-Archive: https://lists.debian.org/msgid-search/20150824145503.GF16060@rosa.stappers.it Approved: robomod@news.nic.it Lines: 37 Organization: linux.* mail to news gateway Sender: robomod@news.nic.it X-Original-Cc: debian-java@lists.debian.org X-Original-Date: Mon, 24 Aug 2015 16:55:03 +0200 X-Original-Message-ID: <20150824145503.GF16060@rosa.stappers.it> X-Original-References: <20150823020212.53513ac0k8m300hw@web-mail.uibk.ac.at> Xref: csiph.com linux.debian.maint.java:8282 On Sun, Aug 23, 2015 at 02:02:12AM +0200, Walter Lenzenweger wrote: > Dear Ladies and Gentlemen! > > I have discovered two problems with the GeoGebra-command Tangent: > > 1. By chance I acchieved to construct a tangent from a point which > does NOT lie on the curve, but the parameter-options for the command > Tangent > only contain Tangent[Point on Curve, Curve] (1) > not Tangent[point, curve]! (2) > > 2. While Tangent works for purpose (2), it does not work for purpose > (1) - for implicit curves at least: > > I have considered an implicit curve (algebraic curve, order 3), a > point P in the plane and the tangent from P to c. > > A = 1 B = 1 P=(-2,1) c: A x³ + B y = 0 > t = Tangent[P,c] > > I see 4 tangents to c through P, but if I change P to (0,0), save > the file,reopen it, two windows appear saying: 'opening file failed' > and a new ggb-window is opened but I cannot open the saved file! > > Of course it would be easy to solve this problem defining > explicitely f(x) = -x^3 instead of c, > but I am interested in tangents in given points of any algebraic > curve which cannot be defined explicitely! > > Best wishes and thanks for clearing this problem! > > Walter Lenzenweger > > P.S. I am using a Dell-notebook XPS L502X, Windows 7 http://catb.org/~esr/faqs/smart-questions.html