Re: Forcing real eigenvalues with 'eigs'?

[Søren Hauberg]

tor, 22 01 2009 kl. 13:35 +0100, skrev Francesco Potortì:
> >Is it possible to force 'eigs' to produce real eigenvalues? I'm
> >computing eigenvalues of a real symmetric matrix, but I'm still getting
> >complex eigenvalues (numerical issues I guess), so it would be nice if I
> >could force them into being real.
> 
> Have you looked at the numbers?  If the imaginary part is very small
> compared to the real one, you can just discard it using real().  If not,
> you may have stability problems.

Yeah, I can just discard them using real (they are indeed quite small).
It just seems to me that it would be better if I could constraint 'eigs'
to working only with real values.

Søren