El 04/08/2014, a las 16:17, Andrea Fani escribió: > Hello, > > I have to solve a generalized eigenvalue problem Ax=sigma B x. > > A is not hermitian. B is singular and is slightly not hermitian (only few > elements breaks the symmetry). > > I used the standard krilov-shur algorithm with a shift and invert > tranformation and it seems to work fine, but I am a bit worried since in the > documentation it is treated only the case with B singular but symmetric. > > Andrea
Symmetric Krylov methods in SLEPc use the B-inner product, so if B is singular we need to do purification of the computed solution to remove directions in the nullspace of B. Non-symmetric Krylov solvers use the standard inner product (not the B-inner product), so purification is not necessary. Jose
