[petsc-users] understanding the eigenvalues of my system

[Matthew Knepley]

On Tue, Aug 6, 2013 at 2:38 PM, Zou (Non-US), Ling <ling.zou at inl.gov> wrote:

> Dear All,
>
> I just explored the user manual v3.4 and I noticed the option
>
> -ksp_compute_eigenvalues
>
> I test it with my problem with ~1000 number of dofs, and it printed out
>
> Iteratively computed eigenvalues
> 0.840692 + 0i
> 0.857247 - 0.235747i
> 0.857247 + 0.235747i
> 0.999993 + 0i
> 1.03457 + 0i
> 2.69763 + 0i
>
> I noticed there are complex numbers... I wonder what does the printout
> info indicate, a good system, a bad system or nothing special?
>

Eigenvalues are complex. This looks like a well-conditioned system, and its
not Hermitian.

   Matt


>
> Best,
>
> Ling
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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