[petsc-users] Krylov-Schur Tolerance

[Jose E. Roman]

> El 19 feb 2017, a las 11:00, Christopher Pierce <cmpierce at WPI.EDU> escribió:
> 
> Thanks,
> 
> Those changes did improve the tolerances of the solutions.  However, I
> still have the same problem.  For certain matrices the error is up to
> 10^4 times as large as the requested tolerances and when using true
> residual the solver gets stuck on a certain residual norm the solutions
> and does not converge.  I dumped the settings that I used which I'm
> attaching here.
> 
> Chris

The settings seem correct.
I would try to solve the problem as a non-symmetric problem: -eps_gen_non_hermitian
Does it give small residuals? If so, the problem may be that your B-matrix is quite bad (high norm or ill-conditioned).

Jose