[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: eignenvalue for nonsymmetric matrix

From: Mike Miller
Subject: Re: eignenvalue for nonsymmetric matrix
Date: Thu, 7 Apr 2005 12:20:43 -0500 (CDT)

On Thu, 7 Apr 2005, Przemek Klosowski wrote:

  a non-symmetric full matrix. Octave gives me the following error:
  error: dgeev failed to converge. The sample problem is below.

  octave:1> stiff = [1,2,3,4;5,6,7,8;9,10,11,12;13,14,15,16]
  octave:2> eig(stiff)
  error: dgeev failed to converge

that is because the matrix you have picked up is degenerate, i.e. its rows are linearly dependent. In fact, it has only two independent rows, as you can see by executing rank(stiff). The eig() function only works for non-degenerate matrices; for degenerate ones you should use svd(). See for details.

If it's not of full rank, it has some zero eigenvalues. eig still works for matrices of less than full rank. On my system, using old Octave, eig returns this:



Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:
How to fund new projects:
Subscription information:

reply via email to

[Prev in Thread] Current Thread [Next in Thread]