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Re: Quadratic Eigen value problems?


From: Søren Hauberg
Subject: Re: Quadratic Eigen value problems?
Date: Thu, 12 Jul 2007 10:40:08 +0200
User-agent: Thunderbird 1.5.0.12 (X11/20070604)

Hi,
Thanks a lot for the answer! I should be able to implement the algorithm now.

Thanks,
  Søren

Fumihiro CHIBA skrev:
Hi,  S!)ren

consider the following problem:
lambda^2 A u + lambda B  u + C u == 0,
where 0 is zero vector; lambda is unknown scalar; u is unknwon vector; A,B and C are given matrices.

introduce auxiliary vector v as follows.
v= lambda u.
the problem is transformed to:
lambda A v + lambda B u == -C u,
lambda u == v.

matrix representation of this problem is
lambda [[B A];[I 0]] * [u;v] == [-C; I][u:v],
where I is unit matrix.
this is a generalized eigenvalue problem.
octave function qz can be applied to this problem.

Reference: SIAM Review Vol. 43 No. 2 pp. 235--286, F. Tisseur and K. Meerbergen, "The quadratic eigenvalue problem"

2007-07-12, 15:52 JST,  "S!)ren Hauberg" <address@hidden> wrote:
Hi,
I just stumbled upon a cool algorithm that I'd like to try out. It requires that I solve a Quadratic Eigen Value problem. The article mentions that I can do this in Matlab using the 'polyeig' function. Unfortunately it seems that Octave doesn't have this function :-(
  Does anybody know how to solve such problems with Octave?

S!)ren



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