Re: Root finding - Bug in Num Recipes - Article 1317 - go-pugleaf

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Re: Root finding - Bug in Num Recipes

#1317

From: Eric Backus
Date: Thu, 19 Nov 1998 00:00

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Ken Laberteaux <klaberte@trc.tellabs.com> writes:

> I am reading the 2nd Edition of _Numerical Recipes in C_.  I am
> specifically looking at laguer.c.
> 
> On p. 373 the line of code which implements Eq 9.5.7 (p. 372) is 
> 
>                h=Csub(g2,RCmul(2.0,Cdiv(f,b)));
> 
> However Eq 9.5.7 (p. 372) makes no reference of the 2, indicating that
> the correct version should be
> 
>                h=Csub(g2,Cdiv(f,b));
> 
> Can anyone shed some light into this inconsistency?

I agree that this appears to be inconsistant, and that your proposed
modification looks correct.

My own code for the Laguerre method does not have the factor of two,
and seems to work well.

-- 
			Eric Backus <eric_backus@hp.com>
			http://labejb.lsid.hp.com/
			(425) 335-2495

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From: Eric Backus <ericb@labejb.lsid.hp.com>
Subject: Re: Root finding - Bug in Num Recipes
Date: 1998/11/19
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