Here's an interesting function that returns the nth root of P. Usage:
halley(2,2) # 2nd root of 2 1.41421356237 2.0**0.5 # check 1.41421356237
halley(7,3) # 3rd root of 7 1.91293118277 7.0**(1./3.) # check 1.91293118277
halley(1000,4) # 4th root of 1000 (duh) 10.0
Maybe the math module is even using something similar (or C internally)? Kirby # thanks to Domingo Gómez Morín # http://www.etheron.net/usuarios/dgomez/Roots.htm def halley(P,n,d=10,x=1.0): # P -- find nth root of this number # n -- whole number root # d -- level of depth for recursion (default 10) # x -- initial value of x (default 1) if d>1: newx = ((n+1.0)*P*x + (n-1)*(x**(n+1)))/((n-1)*P + (n+1)*x**n) return halley(P,n,d-1,newx) else: return x Return-Path: <siegel@eico.com> Delivered-To: edu-sig@python.org Received: from mail.eico.com (unknown [216.216.41.149]) by dinsdale.python.org (Postfix) with SMTP id A4C461CD1F for <edu-sig@python.org>; Fri, 12 May 2000 19:12:00 -0400 (EDT) Received: from siegel ([209.109.224.69]) by mail.eico.com (Lotus SMTP MTA v4.6.4 (830.2 3-23-1999)) with SMTP id 852568DD.007E3246; Fri, 12 May 2000 18:58:24 -0400 From: "Arthur Siegel" <siegel@eico.com> To: "Jeffrey Elkner" <jelkner@yorktown.arlington.k12.va.us>, "PythonEd" <edu-sig@python.org> Date: Fri, 12 May 2000 19:07:54 -0400 Message-ID: <NDBBIAEANKEFIFOFMJHPAEKHCBAA.siegel@eico.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal In-Reply-To: <BCD0C7B9B8B650B6852568DD0069B8B1.0069B9C0852568DD@eico.com> X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6600 Subject: [Edu-sig] Unsubscribe Sender: edu-sig-admin@python.org Errors-To: edu-sig-admin@python.org X-BeenThere: edu-sig@python.org X-Mailman-Version: 2.0beta3 Precedence: bulk List-Id: Python in education <edu-sig.python.org> I was going to wait until Monday, but now prefer to face the week-end with a clearer head. I had written -
Fair enough?
I certainly thought so. But I will take silence as a no in this case. So I guess I've seen this through to the end. I am proud of at least that. Guido: Please remove the EDU-SIG link to PyGeo. It's busted anyway David Ascher: Thanks for listening. To Starship: Please consider my February something (my e-mail archives don't go back far enough to pinpoint) request for a crew account, delivered according to instructions, in good order with receipt acknowledged - withdrawn. To Stephen: I'll settle for the consolation prize. $300, I believe. You have the address. To Kirby: Love to hear Urner on the Transcendentalists. Will be checking your site.