On Sat, Sep 19, 2015 at 6:10 PM, Gideon Simpson <[email protected]> wrote:
> It gives zero pivots on: > Send -ksp_view Matt > -ksp_type gmres -pc_type gamg -mg_coarse_sub_pc_factor_shift_type NONZERO > > It has no problem with: > > -ksp_type gmres -pc_type bjacobi -sub_pc_factor_shift_type NONZERO > > -gideon > > > On Sep 19, 2015, at 12:37 AM, Barry Smith <[email protected]> wrote: > > > > > >> On Sep 18, 2015, at 10:42 PM, Gideon Simpson <[email protected]> > wrote: > >> > >> I’m getting a zero pivot in LU factorization error when I use the gamg > preconditioner. I know there is some issue with my matrix, as I get the > same error if I use pc_type lu in serial, or if I use pc_type bjacobi in > parallel, both of which are corrected by adding -pc_factor_shift_type > NONZERO -sub_pc_factor_shift_type NONZERO, respectively. However, I can’t > quite seem to figure out the analogous command to use for the gamg > preconditioner. > > > > You need to figure out the prefix to the option that is added by gamg > to set it. One way is to run with the gamg options and -help and grep for > factor_shift. > > > > The option is like something like -mg_coarse_pc_factor_shift_type > nonzero or -mg_coarse_sub_pc_factor_shift_type > > > > Barry > > > >> > >> -gideon > >> > > > > -- 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
