petsc-3.7.3 2016-07-24
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# PCML

Use algebraic multigrid preconditioning. This preconditioner requires you provide fine grid discretization matrix. The coarser grid matrices and restriction/interpolation operators are computed by ML, with the matrices coverted to PETSc matrices in aij format and the restriction/interpolation operators wrapped as PETSc shell matrices.

### Options Database Key

### Multigrid options(inherited)

| -pc_mg_cycles <1>: 1 for V cycle, 2 for W | - cycle (MGSetCycles)
| -pc_mg_smoothup <1>: Number of post | - smoothing steps (MGSetNumberSmoothUp)
| -pc_mg_smoothdown <1>: Number of pre | - smoothing steps (MGSetNumberSmoothDown)
| -pc_mg_type <multiplicative>: (one of) additive multiplicative full kascade | - ML options: + -pc_ml_PrintLevel <0>: Print level (ML_Set_PrintLevel)

-pc_ml_maxNlevels <10>: Maximum number of levels (None) -. -pc_ml_maxCoarseSize <1>: Maximum coarsest mesh size (ML_Aggregate_Set_MaxCoarseSize)
-pc_ml_CoarsenScheme <Uncoupled>: (one of) Uncoupled Coupled MIS METIS -. -pc_ml_DampingFactor <1.33333>: P damping factor (ML_Aggregate_Set_DampingFactor)
-pc_ml_Threshold <0>: Smoother drop tol (ML_Aggregate_Set_Threshold) -. -pc_ml_SpectralNormScheme_Anorm <false>: Method used for estimating spectral radius (ML_Set_SpectralNormScheme_Anorm)
-pc_ml_repartition <false>: Allow ML to repartition levels of the heirarchy (ML_Repartition_Activate) -. -pc_ml_repartitionMaxMinRatio <1.3>: Acceptable ratio of repartitioned sizes (ML_Repartition_Set_LargestMinMaxRatio)
-pc_ml_repartitionMinPerProc <512>: Smallest repartitioned size (ML_Repartition_Set_MinPerProc) -. -pc_ml_repartitionPutOnSingleProc <5000>: Problem size automatically repartitioned to one processor (ML_Repartition_Set_PutOnSingleProc)
-pc_ml_repartitionType <Zoltan>: Repartitioning library to use (ML_Repartition_Set_Partitioner) -. -pc_ml_repartitionZoltanScheme <RCB>: Repartitioning scheme to use (None)
-pc_ml_Aux <false>: Aggregate using auxiliary coordinate -based laplacian (None)
-pc_ml_AuxThreshold <0.0>: Auxiliary smoother drop tol (None) -

### See Also

PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), MPSetCycles(), PCMGSetNumberSmoothDown(), PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(), PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(), PCMGSetCycleTypeOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()

Level:intermediate
Location: src/ksp/pc/impls/ml/ml.c
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages