petsc-3.12.5 2020-03-29

SNESSetLagJacobian

Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how often the preconditioner is rebuilt.

Synopsis

#include "petscsnes.h"  
PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)

Logically Collective on SNES

Input Parameters

	snes	- the SNES context
	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 means rebuild at next chance but then never again

Options Database Keys

-snes_lag_jacobian <lag> - Notes: The default is 1 The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 If -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed at the next Newton step but never again (unless it is reset to another value)

Level

intermediate

Location