Set whether or not the Jacobian lagging persists through multiple nonlinear solves


#include "petscsnes.h"  
PetscErrorCode SNESSetLagJacobianPersists(SNES snes, PetscBool flg)

Logically collective

Input Parameters#

  • snes - the SNES context

  • flg - jacobian lagging persists if true

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


Normally when SNESSetLagJacobian() is used, the Jacobian is always rebuilt at the beginning of each new nonlinear solve, this removes that.

This is useful both for nonlinear preconditioning, where it’s appropriate to have the Jacobian be stale by several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several timesteps may present huge efficiency gains.

See Also#

SNES, SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC(), SNESSetLagJacobianPersists()`





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