PCGAMGSetAggressiveSquareGraph#

Use graph square, \(A^T A\), for aggressive coarsening. Coarsening is slower than the alternative (MIS-2), which is faster and uses less memory

Synopsis#

Logically Collective

Input Parameters#

  • pc - the preconditioner context

  • b - default true

Options Database Key#

  • -pc_gamg_aggressive_square_graph <bool,default=true> - the flag

Notes#

If b is PETSC_FALSE then MIS-k is used for aggressive coarsening, see PCGAMGMISkSetAggressive()

Squaring the matrix to perform the aggressive coarsening is slower and requires more memory than using MIS-k, but may result in a better preconditioner that converges faster.

See Also#

the Users Manual section on PCGAMG, the Users Manual section on PCMG, KSP: Linear System Solvers, PCGAMG, PCGAMGSetThreshold(), PCGAMGSetAggressiveLevels(), PCGAMGMISkSetAggressive(), PCGAMGMISkSetMinDegreeOrdering(), PCGAMGSetLowMemoryFilter()

Level#

intermediate

Location#

src/ksp/pc/impls/gamg/agg.c

Examples#

src/ksp/ksp/tutorials/ex56.c

Implementations#

PCGAMGSetAggressiveSquareGraph_AGG() in src/ksp/pc/impls/gamg/agg.c


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