[petsc-users] targetting specific eigenvectors

[Jose E. Roman]

El 14/08/2011, a las 21:21, Nachiket Gokhale escribió:

> I am solving a coupled structural-acoustic calculation, and I want to
> find the most important "coupled modes", i.e. the modes which transfer
> the most energy between the structure and the fluid.  One way to do
> this would be to solve the first N modes of the full generalized
> eigenproblem (Kx=Mx), and compute a measure of the coupling (
> something like \pi = u'Sp ),  where S is the coupling matrix, u is the
> displacement and p is there pressure. One could then sort the coupled
> modes according to \pi. However, important coupled modes which do not
> lie in the first "N" modes may not be found (unless there are matrix
> structuring results that I am not aware of).
> 
> Are there any algorithms that guarantee that find first N_c important
> coupled modes as defined by an user defined criterion, and are there
> any code s that implement them?
> 
> The only reference I could find was
> 
> Alan R. Tackett, Massimiliano Di Ventra, Targeting specific
> eigenvectors and eigenvalues of a given Hamiltonian using arbitrary
> selection criteria, PHYSICAL REVIEW B 66, 245104  2002.
> 
> Sorry for the slightly OT discussion.
> 
> Thanks,
> 
> Nachiket

In SLEPc 3.1 there is the possibility of setting a user-defined selection criterion with EPSSetEigenvalueComparison. However, currently this only allows for criteria based on the eigenvalues and not on the eigenvectors. We will see if it is feasible to add this possibility for the next version.

Jose