[petsc-users] SLEPSc and spectrum slicing

[Jose E. Roman]

To answer the question I would need more information. 
- Is your B matrix symmetric? Is it symmetric positive-definite?
- Do your A and B matrices have a special block structure?
- Is your spectrum symmetric with respect to the origin?
- How many eigenvalues do you need? (in percentage)

Jose

> El 19 ene 2026, a las 11:17, TARDIEU Nicolas via petsc-users <petsc-users at mcs.anl.gov> escribió:
> 
> Dear PETSc team,
> 
> I am using SLEPc to solve a generalized non-symmetric eigenvalue problem. The underlying physical problem—coupled vibrations of an acoustic fluid enclosed in an elastic container—is actually conservative, so all eigenvalues and eigenvectors are real. The literature shows that a change of basis exists that makes the problem symmetric, but this transformation is computationally  expensive.
> 
> Since I need to compute a large number of eigenvalues, I would like to use spectrum slicing, which is only available for symmetric matrices. I am not familiar with the internal workings of spectrum slicing in SLEPc, and I am wondering whether it could be possible to force the algorithm to handle these (pseudo-)non-symmetric matrices, given that the actual spectrum is real.
> 
> Thanks,
> Regards,
> --
> Nicolas Tardieu
> Ing PhD Computational Mechanics
> EDF - R&D Dpt ERMES
> PARIS-SACLAY, FRANCE
> 
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