|-pc_pfmg_its <its> number of iterations of PFMG to use as preconditioner|
|-pc_pfmg_num_pre_relax <steps> number of smoothing steps before coarse grid|
|-pc_pfmg_num_post_relax <steps> number of smoothing steps after coarse grid|
|-pc_pfmg_tol <tol> tolerance of PFMG|
|-pc_pfmg_relax_type||- relaxation type for the up and down cycles, one of Jacobi,Weighted-Jacobi,symmetric-Red/Black-Gauss-Seidel,Red/Black-Gauss-Seidel|
|-pc_pfmg_rap_type||- type of coarse matrix generation, one of Galerkin,non-Galerkin|
This must be used with the MATHYPRESTRUCT matrix type. This is less general than in hypre, it supports only one block per process defined by a PETSc DMDA.