[petsc-users] gamg and zero pivots

[Gideon Simpson]

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

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