petsc-master 2020-09-23
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SNESGetLagPreconditioner

Indicates how often the preconditioner is rebuilt

Synopsis

#include "petscsnes.h"  
PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
Not Collective

Input Parameter

snes - the SNES context

Output Parameter

lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

Options Database Keys

-snes_lag_jacobian_persists <true,false> - sets the persistence
-snes_lag_jacobian <- 2,1,2,...> - sets the lag
-snes_lag_preconditioner_persists <true,false> - sets the persistence
-snes_lag_preconditioner <- 2,1,2,...> - sets the lag

Notes

The default is 1 The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

See Also

SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner(), SNESSetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

Level

intermediate

Location

src/snes/interface/snes.c
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages