Matlab's root finder for polynomials finds the eigen values of the

companion matrix of the polynomial. In a way sort of ironic.

Jack

help-octave @ bevo.che.wisc.edu at INTERNET

07/05/97 10:18 AM

To: hoffmann @ ehmgs2.et.tu-dresden.de at INTERNET@CCMAIL

cc: help-octave @ bevo.che.wisc.edu at INTERNET@CCMAIL, farnswor @

cob.ohio-state.edu at INTERNET@CCMAIL (bcc: Jack A Walker/BII)

Subject: Re: Root finding procedure?

The thing that comes to mind is fsolve. Write a m-file which takes x as

an argument and return det(H). Use fsolve and it will return the value

of x that makes det(H) as close to zero as possible. Of course there

will be a problem with multiple roots and so the answer you get will

depend on the starting value you give to fsolve. I don't know of one

that returns all the roots.

On Fri, 4 Jul 1997, Thomas Hoffmann wrote:

> I am looking for octave- or matlab-code, that allows me to find the

> roots of the polynomial of x that results from det(H)=0, where the Hij

> are polynomials in x theirself.

> E.g.: find the roots x for

>

> 3x-4 2x+9

> det ( ) = 0

> -x+22 4x-11

>

> I can program such a procedure myself (with successive convolution),

> but this problem seems standard enough to me, that there could be a

> procedure out there in octave-land.

> Any hints?

>

> Thomas Hoffmann.

>

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Date: Sat, 5 Jul 1997 13:12:26 -0400 (EDT)

From: Heber Farnsworth <

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Subject: Re: Root finding procedure?

To: Thomas Hoffmann <

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