[R] newtons method

John C Nash nashjc at uottawa.ca
Tue May 12 14:58:03 CEST 2009

Finding polynomial roots is not a problem where one wants a quick and dirty code. There are a lot of pitfalls, especially if there are roots that are multiples, and there has been a lot of work on this problem. See http://en.wikipedia.org/wiki/Category:Root-finding_algorithms .

And Uwe may not be aware that optim() is contra-recommended for functions of 1 variable, which seems to be the problem here. But there is 



Message: 130
Date: Tue, 12 May 2009 11:12:51 +0200
From: Uwe Ligges <ligges at statistik.tu-dortmund.de>
Subject: Re: [R] newtons method
To: Kon Knafelman <konk2001 at hotmail.com>
Cc: r-help at stat.math.ethz.ch
Message-ID: <4A093D93.1020702 at statistik.tu-dortmund.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Kon Knafelman wrote:

> > Hi,
> > 
> > Does anyone know how to code newton's method for finding the roots of polynomial functions? im not sure whether i need to do this manually, or just code something with a loop to stop when it gets to the desired result

See ?optim for optimization methods.

Uwe Ligges

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