petsc-3.14.6 2021-03-30
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PCGAMGSetSquareGraph

 Square the graph, ie. compute A'*A before aggregating it

Synopsis

#include "petscpc.h" 
PetscErrorCode PCGAMGSetSquareGraph(PC pc, PetscInt n)
Logically Collective on PC

Input Parameters

pc - the preconditioner context
n - 0, 1 or more

Options Database Key

-pc_gamg_square_graph <n,default = 1> - number of levels to square the graph on before aggregating it

Notes

Squaring the graph increases the rate of coarsening (aggressive coarsening) and thereby reduces the complexity of the coarse grids, and generally results in slower solver converge rates. Reducing coarse grid complexity reduced the complexity of Galerkin coarse grid construction considerably.

See Also

PCGAMGSetSymGraph(), PCGAMGSetThreshold()

Level

intermediate

Location

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

Implementations

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

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