PCAIRSetStrongThreshold

Sets the strong threshold used in the PCAIR CF splitting

Synopsis

PETSC_EXTERN PetscErrorCode PCAIRSetStrongThreshold(PC pc, PetscReal input_real)

Logically Collective

Input Parameters

• pc - the PCAIR preconditioner context

• input_real - the strong threshold used in the CF splitting

Options Database Key

• -pc_air_strong_threshold strong_threshold - the strong threshold used in the CF splitting; defaults to 0.5

Note

This controls how strong a connection must be to influence the CF splitting; a larger threshold treats fewer connections as strong, typically producing sparser coarse grids and cheaper cycles but slower convergence, while a smaller threshold does the opposite. Values in [0, 1) are required, with 0.5 a reasonable default. For the CF_DIAG_DOM splitting this instead sets the target diagonal dominance ratio, and for the CF_CR splitting it sets the target compatible relaxation rate, the contraction one application of the F-point smoother must achieve (around 0.1 is a reasonable choice there).

See Also

KSP: Linear System Solvers, PCAIR, PCAIRGetStrongThreshold(), PCAIRSetCFSplittingType(), CFSplittingType

Level

intermediate

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Index of all manual pages