It gives zero pivots on: -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 >> >
