[petsc-users] GAMG Indefinite

Sun May 22 17:02:41 CDT 2016

I thought you would have this also, so add it (I assume this is 3D
elasticity):

-pc_gamg_square_graph 1
-mg_levels_ksp_type chebyshev
-mg_levels_pc_type sor

Plus what I just mentioned:

-mg_levels_esteig_ksp_type cg
-mg_levels_ksp_chebyshev_esteig 0,0.05,0,1.05

Just for diagnostics add:

-mg_levels_esteig_ksp_max_it 50
-mg_levels_esteig_ksp_monitor_singular_value
-ksp_view

On Sun, May 22, 2016 at 5:38 PM, Sanjay Govindjee <s_g at berkeley.edu> wrote:

> Mark,
>   Can you give me the full option line that you want me to use?  I
> currently have:
>
> -ksp_type cg -ksp_monitor -ksp_chebyshev_esteig_random -log_view -pc_type
> gamg -pc_gamg_type agg -pc_gamg_agg_nsmooths 1 -options_left
>
> -sanjay
>
>
> On 5/22/16 2:29 PM, Mark Adams wrote:
>
> Humm, maybe we have version mixup:
>
> src/ksp/ksp/impls/cheby/cheby.c:    ierr =
> PetscOptionsBool("-ksp_chebyshev_esteig_random","Use random right hand side
> for
> estimate","KSPChebyshevEstEigSetUseRandom",cheb->userandom,&cheb->userandom
>
> Also, you should use CG. These other options are the defaults but CG is
> not:
>
> -mg_levels_esteig_ksp_type cg
> -mg_levels_esteig_ksp_max_it 10
> -mg_levels_ksp_chebyshev_esteig 0,0.05,0,1.05
>
> Anyway. you can also run with -info, which will be very noisy, but just
> grep for GAMG and send me that.
>
> Mark
>
>
>
> On Sat, May 21, 2016 at 6:03 PM, Sanjay Govindjee <s_g at berkeley.edu>
> wrote:
>
>> Mark,
>>   I added the option you mentioned but it seems not to use it;
>> -options_left reports:
>>
>> #PETSc Option Table entries:
>> -ksp_chebyshev_esteig_random
>> -ksp_monitor
>> -ksp_type cg
>> -log_view
>> -options_left
>> -pc_gamg_agg_nsmooths 1
>> -pc_gamg_type agg
>> -pc_type gamg
>> #End of PETSc Option Table entries
>> There is one unused database option. It is:
>> Option left: name:-ksp_chebyshev_esteig_random (no value)
>>
>>
>>
>> On 5/21/16 12:36 PM, Mark Adams wrote:
>>
>> Barry, this is probably the Chebyshev problem.
>>
>> Sanjay, this is fixed but has not yet been moved to the master branch.
>> You can fix this now with with -ksp_chebyshev_esteig_random.  This should
>> recover v3.5 semantics.
>>
>> Mark
>>
>> On Thu, May 19, 2016 at 2:42 PM, Barry Smith < <bsmith at mcs.anl.gov>
>> bsmith at mcs.anl.gov> wrote:
>>
>>>
>>>    We see this occasionally, there is nothing in the definition of GAMG
>>> that guarantees a positive definite preconditioner even if the operator was
>>> positive definite so we don't think this is a bug in the code. We've found
>>> using a slightly stronger smoother, like one more smoothing step seems to
>>> remove the problem.
>>>
>>>    Barry
>>>
>>> > On May 19, 2016, at 1:07 PM, Sanjay Govindjee <s_g at berkeley.edu>
>>> wrote:
>>> >
>>> > I am trying to solve a very ordinary nonlinear elasticity problem
>>> > using -ksp_type cg -pc_type gamg in PETSc 3.7.0, which worked fine
>>> > in PETSc 3.5.3.
>>> >
>>> > The problem I am seeing is on my first Newton iteration, the Ax=b
>>> > solve returns with and Indefinite Preconditioner error
>>> (KSPGetConvergedReason == -8):
>>> > (log_view.txt output also attached)
>>> >
>>> >   0 KSP Residual norm 8.411630828687e-02
>>> >   1 KSP Residual norm 2.852209578900e-02
>>> >   NO CONVERGENCE REASON:  Indefinite Preconditioner
>>> >   NO CONVERGENCE REASON:  Indefinite Preconditioner
>>> >
>>> > On the next and subsequent Newton iterations, I see perfectly normal
>>> > behavior and the problem converges quadratically.  The results look
>>> fine.
>>> >
>>> > I tried the same problem with -pc_type jacobi as well as super-lu, and
>>> mumps
>>> > and they all work without complaint.
>>> >
>>> > My run line for GAMG is:
>>> > -ksp_type cg -ksp_monitor -log_view -pc_type gamg -pc_gamg_type agg
>>> -pc_gamg_agg_nsmooths 1 -options_left
>>> >
>>> > The code flow looks like:
>>> >
>>> > ! If no matrix allocation yet
>>> > if(Kmat.eq.0) then
>>> >   call MatCreate(PETSC_COMM_WORLD,Kmat,ierr)
>>> >   call
>>> MatSetSizes(Kmat,numpeq,numpeq,PETSC_DETERMINE,PETSC_DETERMINE,ierr)
>>> >   call MatSetBlockSize(Kmat,nsbk,ierr)
>>> >   call MatSetFromOptions(Kmat, ierr)
>>> >   call MatSetType(Kmat,MATAIJ,ierr)
>>> >   call
>>> MatMPIAIJSetPreallocation(Kmat,PETSC_NULL_INTEGER,mr(np(246)),PETSC_NULL_INTEGER,mr(np(247)),ierr)
>>> >   call
>>> MatSeqAIJSetPreallocation(Kmat,PETSC_NULL_INTEGER,mr(np(246)),ierr)
>>> > endif
>>> >
>>> > call MatZeroEntries(Kmat,ierr)
>>> >
>>> > ! Code to set values in matrix
>>> >
>>> > call MatAssemblyBegin(Kmat, MAT_FINAL_ASSEMBLY, ierr)
>>> > call MatAssemblyEnd(Kmat, MAT_FINAL_ASSEMBLY, ierr)
>>> > call MatSetOption(Kmat,MAT_NEW_NONZERO_LOCATIONS,PETSC_TRUE,ierr)
>>> >
>>> > ! If no rhs allocation yet
>>> > if(rhs.eq.0) then
>>> >   call VecCreate        (PETSC_COMM_WORLD, rhs, ierr)
>>> >   call VecSetSizes      (rhs, numpeq, PETSC_DECIDE, ierr)
>>> >   call VecSetFromOptions(rhs, ierr)
>>> > endif
>>> >
>>> > ! Code to set values in RHS
>>> >
>>> > call VecAssemblyBegin(rhs, ierr)
>>> > call VecAssemblyEnd(rhs, ierr)
>>> >
>>> > if(kspsol_exists) then
>>> >   call KSPDestroy(kspsol,ierr)
>>> > endif
>>> >
>>> > call KSPCreate(PETSC_COMM_WORLD, kspsol   ,ierr)
>>> > call KSPSetOperators(kspsol, Kmat, Kmat, ierr)
>>> > call KSPSetFromOptions(kspsol,ierr)
>>> > call KSPGetPC(kspsol, pc ,      ierr)
>>> >
>>> > call PCSetCoordinates(pc,ndm,numpn,hr(np(43)),ierr)
>>> >
>>> > call KSPSolve(kspsol, rhs, sol, ierr)
>>> > call KSPGetConvergedReason(kspsol,reason,ierr)
>>> >
>>> > ! update solution, go back to the top
>>> >
>>> > reason is coming back as -8 on my first Ax=b solve and 2 or 3 after
>>> that
>>> > (with gamg).  With the other solvers it is coming back as 2 or 3 for
>>> > iterative options and 4 if I use one of the direct solvers.
>>> >
>>> > Any ideas on what is causing the Indefinite PC on the first iteration
>>> with GAMG?
>>> >
>>> > Thanks in advance,
>>> > -sanjay
>>> >
>>> > --
>>> > -----------------------------------------------
>>> > Sanjay Govindjee, PhD, PE
>>> > Professor of Civil Engineering
>>> >
>>> > 779 Davis Hall
>>> > University of California
>>> > Berkeley, CA 94720-1710
>>> >
>>> > Voice:  +1 510 642 6060 <%2B1%20510%20642%206060>
>>> > FAX:    +1 510 643 5264 <%2B1%20510%20643%205264>
>>> >
>>> > s_g at berkeley.edu
>>> > http://www.ce.berkeley.edu/~sanjay
>>> >
>>> > -----------------------------------------------
>>> >
>>> > Books:
>>> >
>>> > Engineering Mechanics of Deformable
>>> > Solids: A Presentation with Exercises
>>> >
>>> >
>>> http://www.oup.com/us/catalog/general/subject/Physics/MaterialsScience/?view=usa&ci=9780199651641
>>> > http://ukcatalogue.oup.com/product/9780199651641.do
>>> > http://amzn.com/0199651647
>>> >
>>> >
>>> > Engineering Mechanics 3 (Dynamics) 2nd Edition
>>> >
>>> > http://www.springer.com/978-3-642-53711-0
>>> > http://amzn.com/3642537111
>>> >
>>> >
>>> > Engineering Mechanics 3, Supplementary Problems: Dynamics
>>> >
>>> > http://www.amzn.com/B00SOXN8JU
>>> >
>>> >
>>> > -----------------------------------------------
>>> >
>>> > <log_view.txt>
>>>
>>>
>>
>> --
>> -----------------------------------------------
>> Sanjay Govindjee, PhD, PE
>> Professor of Civil Engineering
>>
>> 779 Davis Hall
>> University of California
>> Berkeley, CA 94720-1710
>>
>> Voice:  +1 510 642 6060
>> FAX:    +1 510 643 5264s_g at berkeley.eduhttp://www.ce.berkeley.edu/~sanjay
>> -----------------------------------------------
>>
>> Books:
>>
>> Engineering Mechanics of Deformable
>> Solids: A Presentation with Exerciseshttp://www.oup.com/us/catalog/general/subject/Physics/MaterialsScience/?view=usa&ci=9780199651641http://ukcatalogue.oup.com/product/9780199651641.dohttp://amzn.com/0199651647
>>
>> Engineering Mechanics 3 (Dynamics) 2nd Editionhttp://www.springer.com/978-3-642-53711-0http://amzn.com/3642537111
>>
>> Engineering Mechanics 3, Supplementary Problems: Dynamics http://www.amzn.com/B00SOXN8JU
>>
>> -----------------------------------------------
>>
>>
>
>
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