On 12/17/25 18:55, Yiliang Wang wrote:
I think I have found the solution. I use add -ksp_norm_type unpreconditioned
flag when run the simulation.
My suggestion is that it will be better if this flag is automatically turned
on when using petsc CG. Otherwise, the convergence test is not consistent
between the built-in CG and petsc CG.
Ah, that's an interesting observation -- nice job figuring this out! I'm not
sure any of us ever realized that. Is there a way to set this flag in the
program, rather than on the command line? Would you like to see if you could
write a patch that does that? Presumably, one would make this modification here:
https://github.com/dealii/dealii/blob/master/source/lac/petsc_solver.cc#L327-L335
I don't know what we should do about the other PETSc solvers. Presumably, we
would want to make these similar to the deal.II solvers as well, but I'd be
happy to fix one of them at a time.
Best
W.
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