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From: "Michael Nikki" <niqmk@yahoo.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Eigenvalues Problem?
Date: Sun, 30 Dec 2007 10:10:19 +0000 (UTC)
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Inf <infinitysquared@gmail.com> wrote in message 
> Michel,
> 
> Two points:
> 
> 1) you are getting your traces wrong - they
> should be the sum of the diagonal elements
> 
> so  If A=2x2:
> > a b
> > c d
> 
> then trace A =a+d not a+b, as you write.

Yeah, I Apologize from that.

> 
> 2) generally, the characteristic polynomial is
> obtained from det(A-lambda*I)
> where I is the identity matrix, e.g. in the 2x2 case
> I is
> 
> 1 0
> 0 1
> 
> So you need to read up how to work out
> determinants.
> 
> Hope this helps.
> 
> Inf.

You mean that when getting lambda 1-n, I can get from
det(A-lambda*I)?

So how to get Sk from

(-1)^n lambda^n + (-1)^(n-1) S1 lambda^(n-1) + (-1)^(n-2) Sk
> > lambda^(k) + Sn

It says sub matrix from A (k x k). What the mean of sub
matrix? Sorry I'm very newbie from this. Thanks for your answer.