| -pc_composite_type <type: one of multiplicative, additive, symmetric_multiplicative, special> | - Sets composite preconditioner type | |
| -pc_use_amat | - activates PCSetUseAmat() | |
| -pc_composite_pcs | - <pc0,pc1,...> list of PCs to compose |
Notes: To use a Krylov method inside the composite preconditioner, set the PCType of one or more inner PCs to be PCKSP. Using a Krylov method inside another Krylov method can be dangerous (you get divergence or the incorrect answer) unless you use KSPFGMRES as the outer Krylov method To use a different operator to construct one of the inner preconditioners first call PCCompositeGetPC(), then call PCSetOperators() on that PC.