Set whether or not the Jacobian lagging persists through multiple nonlinear solves
snes - the
flg - jacobian lagging persists if true
Options Database Keys#
-snes_lag_jacobian_persists <true,false> - sets the persistence through multiple SNES solves
-snes_lag_jacobian <- 2,1,2,…> - sets the lag
-snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
-snes_lag_preconditioner <- 2,1,2,…> - sets the lag
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.