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.
-gideon
