That makes sense. Thanks for the quick reply! On Fri, Nov 11, 2022 at 2:59 PM Matthew Knepley <[email protected]> wrote:
> 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/> >
