David Scott <d.scott at ed.ac.uk> writes:
> I forgot to say that the program ran on 128 MPI processes with the
> following arguments
> -pc_type gamg -pc_gamg_agg_nsmooths 1 -ksp_rtol 0.0001
Your problem is singular, as can be seen here:
-mg_coarse_pc_type svd -mg_coarse_pc_svd_monitor
SVD: condition number 4.795499711084e+15, 0 of 643 singular values are
(nearly) zero
SVD: smallest singular values: 1.007601359796e-11 1.599999673167e+02
1.599999753343e+02 1.599999841127e+02 1.599999906466e+02
SVD: largest singular values : 4.527760228588e+04 4.558254786213e+04
4.648975485549e+04 4.809775098939e+04 4.831952029788e+04
Additionally, it appears that your right hand side is inconsistent. The
null space is not the constant so I would indict the discretization
becoming degenerate somewhere.
