[petsc-users] Matrix-free generalised eigenvalue problem

[Quentin Chevalier]

Hello PETSc Users,

I have a generalised eigenvalue problem : Ax= lambda Bx
I used to have only A as a matrix-free method, I used mumps and an LU
preconditioner, everything worked fine.

Now B is matrix-free as well, and my solver is returning an error :
"MatSolverType mumps does not support matrix type python", which is ironic
given it seem to handle A quite fine.

I have read in the user manual here
<https://slepc.upv.es/documentation/slepc.pdf#section.8.2> that there some
methods may require additional methods to be supplied for B like
MATOP_GET_DIAGONAL but it's unclear to me exactly what I should be
implementing and what is the best solver for my case.

A is hermitian, B is hermitian positive but not positive-definite or real.
Therefore I have specified a GHEP problem type to the EPS object.

I use PETSc in complex mode through the petsc4py bridge.

Any help on how to get EPS to work for a generalised matrix-free case would
be welcome. Performance is not a key issue here - I have a tractable high
value case on hand.

Thank you for your time,

Quentin
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