[petsc-users] infinite loop with NEWTONTR?

[Norihiro Watanabe]

I cannot surely say my Jacobian for this particular problem is correct, as
I have not checked it. For a smaller problem, I've already checked its
correctness using -snes_type test or -snes_compare_explicit (but linear
solve and nonlinear solve with FD one need a few more iterations than with
my Jacobian). To make it sure, now I started -snes_type test for the
problem and will update you once it finished. By the way, I'm waiting the
calculation for more than three hours now. Is it usual for a large problem
(>1e6 dof) or is there something wrong?





On Mon, Apr 28, 2014 at 6:34 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   I have run your code. I changed to use -snes_type newtonls and also
> -snes_mf_operator  there is something wrong with your Jacobian:
>
>   Without -snes_mf_operator
>  0 SNES Function norm 1.821611413735e+03
>     0 KSP Residual norm 1821.61
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     1 KSP Residual norm 0.000167024
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     2 KSP Residual norm 7.66595e-06
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     3 KSP Residual norm 4.4581e-07
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     4 KSP Residual norm 3.77537e-08
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     5 KSP Residual norm 2.20453e-09
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     6 KSP Residual norm 1.711e-10
>   Linear solve converged due to CONVERGED_RTOL iterations 6
>
> with -snes_mf_operator
>
>   0 SNES Function norm 1.821611413735e+03
>     0 KSP Residual norm 1821.61
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     1 KSP Residual norm 1796.39
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     2 KSP Residual norm 1786.2
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     3 KSP Residual norm 1741.11
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     4 KSP Residual norm 1733.92
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     5 KSP Residual norm 1726.57
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     6 KSP Residual norm 1725.35
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     7 KSP Residual norm 1723.89
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     8 KSP Residual norm 1715.41
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>     9 KSP Residual norm 1713.72
>     Linear solve converged due to CONVERGED_ITS iterations 1
>     Linear solve converged due to CONVERGED_RTOL iterations 1
>    10 KSP Residual norm 1702.84
>     Linear solve converged due to CONVERGED_ITS iterations 1
>
> …
>
>   This means your Jacobian is wrong. Your first order of business is to
> fix your Jacobian. I noticed in previous emails your discussion with Jed
> about switching to MatGetLocalSubMatrix() and using -snes_type test  YOU
> NEED TO DO THIS. You will get no where with an incorrect Jacobian. You need
> to fix your Jacobian before you do anything else! No amount of other
> options or methods will help you with a wrong Jacobian! Once you have a
> correct Jacobian if you still have convergence problems let us know and we
> can make further suggestions.
>
>   Barry
>
> On Apr 25, 2014, at 7:31 AM, Norihiro Watanabe <norihiro.w at gmail.com>
> wrote:
>
> > Hi,
> >
> > In my simulation, nonlinear solve with the trust regtion method got
> stagnent after linear solve (see output below). Is it possible that the
> method goes to inifite loop? Is there any parameter to avoid this situation?
> >
> >   0 SNES Function norm 1.828728087153e+03
> >     0 KSP Residual norm 91.2735
> >     Linear solve converged due to CONVERGED_ITS iterations 1
> >     Linear solve converged due to CONVERGED_RTOL iterations 3
> >     1 KSP Residual norm 3.42223
> >   Linear solve converged due to CONVERGED_STEP_LENGTH iterations 1
> >
> >
> > Thank you in advance,
> > Nori
>
>


-- 
Norihiro Watanabe
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