Re: Root finding procedure?

[Jack A Walker/BII]

  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 address@hidden
  cc:   help-octave @ bevo.che.wisc.edu at address@hidden, farnswor @
        cob.ohio-state.edu at address@hidden (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 <address@hidden>
Subject: Re: Root finding procedure?
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