From the manual page
SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in
the nonlinear solve.
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 indicates rebuild preconditioner at next
chance but then never rebuild after that
On Sep 30, 2012, at 12:20 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> -snes_lag_preconditioner LAG
>
> where LAG is the number of iterations to lag the factorization.
>
> On Sun, Sep 30, 2012 at 1:14 AM, Gong Ding <gdiso at ustc.edu> wrote:
> Hi,
> I'd like to try following strategy:
> For a nonlinear solver, at the first Newton step, do a complete LU
> factorization, and use the factorized matrix as preconditioner matrix in the
> following iteration.
>
> How to implement this in petsc?
>
> Gong Ding
>
>
>
>
>
>
