On Thu, Mar 12, 2020 at 5:59 PM Jed Brown <[email protected]> wrote: > Pierre Jolivet <[email protected]> writes: > > > Hello, > > Has there been any follow-up on this > https://lists.mcs.anl.gov/pipermail/petsc-users/2015-January/024020.html < > https://lists.mcs.anl.gov/pipermail/petsc-users/2015-January/024020.html>? > > Given a 3x3 MatNest A = [A_00,0,0 ; 0,A_11,0 ; 0,0,A_22], I’d like to > setup a two-way fieldsplit coupling [A_00,0 ; 0,A_11] and [A_22] but I > can’t figure out the proper options. > > Are you looking for a Schur split or additive/multiplicative? >
-pc_fieldsplit_field_0 0,1 -pc_fieldsplit_field_1 2 -pc_fieldsplit_type schur I believe. Matt > > Jed, in this answer > https://lists.mcs.anl.gov/pipermail/petsc-users/2015-January/023993.html < > https://lists.mcs.anl.gov/pipermail/petsc-users/2015-January/023993.html>, > you recommend not to use MatNest. What would you recommend instead? > > See src/snes/examples/tutorials/ex28.c for my preferred approach. > -- 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/>
