[petsc-users] Random initial states of EPSSolve

[Yang Bo (Asst Prof)]

Hi everyone,

I am diagonalising a large symmetric real matrix for its null space (highly degenerate eigenstates with zero eigenvalues). I am using krylovschur which is variational, which is supposed to start with a set of random initial vectors. They will eventually converge to random vectors in the null space.

The problem is that if I run the EPSSOLVE with the same set of parameters (e.g. -eps_ncv and -eps_mpd), I always get the same eigenstates in the null space. This implies that the solver always start the same set of initial “random” vectors.

How does petsc generate the initial random vectors for krylovschur? Is there a way for me to generate different random initial vectors every time I run the diagonalisation (of the same matrix)?

Thanks, and stay safe and healthy!

Cheers,

Yang Bo
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