[Cc'ing petsc-users since people may be interested.] Matteo Parsani <parsani.mat...@gmail.com> writes:
> Hi Jed, > do you know if in PETSc we can start a Krylov iteration with problematic > eigenmodes in the Krylov subspace at the beginning of the iteration? Deflation is identical to a Galerkin coarse grid correction. I would use PCMG to create a two-level method. Write your deflation space into the prolongation operator and use Galerkin. You can compose a PCMG with other preconditioners. I would leave DGMRES to only deal with adaptive identification of those problematic modes. Note that the DGMRES basis vectors will be global, but when you provide vectors a priori, you are free to localize them. > Machinery should be there already because we see that this is used when > GMRES stagnates. > > Thanks, > > -- > Matteo
