On Fri, Nov 11, 2022 at 5:57 PM Alexander Lindsay <[email protected]> wrote:
> Under what conditions can I use LSC preconditioning for field split > problems with Schur? Let's imagine that all I've done is called > SNESetJacobian with global A and P and provided the index sets for 0 and 1. > Based off of the documentation on the man page > https://petsc.org/release/docs/manualpages/PC/PCLSC/ it seems like I'd > have to do something more programmatically, e.g. > > PetscObjectCompose((PetscObject)Sp,"LSC_L",(PetscObject)L); > PetscObjectCompose((PetscObject)Sp,"LSC_Lp",(PetscObject)Lp); > > If I try to naively get LSC preconditioning from the command line without > doing something like the above, then I get SUBPC_ERROR. Is this to be > expected? > Yes. PETSc does not have information about the operators or discretizations, and thus it cannot make auxiliary operators like the pressure Laplacian. Thanks, Matt > 0 Nonlinear |R| = 4.164062e-02 > 0 Linear |R| = 4.164062e-02 > Linear solve did not converge due to DIVERGED_PC_FAILED iterations 0 > PC failed due to SUBPC_ERROR > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
