[petsc-users] Unable to use SNESSetConvergenceTest()

[behzad baghapour]

Dear Developers,

I need to change "rtol" manually  for each KSP linear solver in each SNES
iteration (some sort of inexact Newton method).

I decided to use SNESSetConvergenceTest() as bellow:

in main code:

ierr = SNESSetConvergenceTest( snes, SNESConvTest, PETSC_NULL, PETSC_NULL
); CHKERRQ( ierr );

in convergence function:

PetscErrorCode SNESConvTest( SNES snes, PetscInt it, PetscReal xn,
PetscReal pn, PetscReal fn, SNESConvergedReason* res, void* ctx)
{
    KSP ksp2;
    PetscReal rtol, atol;
    SNESGetKSP ( snes, &ksp2 );
    KSPGetTolerances  ( ksp2, &rtol, PETSC_NULL, PETSC_NULL, PETSC_NULL );
    SNESGetTolerances ( snes, &atol, PETSC_NULL, PETSC_NULL, PETSC_NULL,
PETSC_NULL );
    if( fn > 1e-3 ){
        rtol = 0.01;
    }else{
        rtol = 1e-5;
    }
    KSPSetTolerances( ksp2, rtol, PETSC_NULL, PETSC_NULL, PETSC_NULL );
    if( fn < atol ){
        *res = SNES_CONVERGED_FNORM_ABS;
        return 0;
    }else{
        *res = SNES_CONVERGED_ITERATING;
    }
}

BUT I really don't know how to control the convergence criterion for SNES.
So when I run my previous code with the new convergence test I received
divergence error after "first iteration":

Linear solve did not converge due to DIVERGED_DTOL iterations 0
Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE

How should I possibly deal with this??

Thanks a lot,
BehZad
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20111226/f8605b43/attachment.htm>