[petsc-users] Issue of mg_coarse_ksp not converge

Matthew Knepley knepley at gmail.com
Mon Oct 2 09:48:48 CDT 2017 

On Mon, Oct 2, 2017 at 10:43 AM, Wenbo Zhao <zhaowenbo.npic at gmail.com>
wrote:

> Mark,
>
> Thanks for your reply.
>
> On Mon, Oct 2, 2017 at 9:51 PM, Mark Adams <mfadams at lbl.gov> wrote:
>
>> Please send the output with -st_ksp_view and -st_ksp_monitor and we can
>> start to debug it.
>>
>> Test 1 with nonsmooth and preonly is OK
> zhaowenbo at ubuntu:~/test_slepc/SPARK/spark$ make NCORE=1 runkr_nonsmooth
> mpirun -n 1 ./step-41 \
>    -st_ksp_type gmres  -st_ksp_view -st_ksp_monitor  \
>    -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 0 \
>    -st_ksp_view  -mata AMAT.dat -matb BMAT.dat \
>    -st_mg_coarse_ksp_type preonly   -st_mg_coarse_ksp_monitor  \
>    -eps_nev 1 -eps_ncv 10  -eps_monitor  -log_view > log_nonsmooth 2>&1
>
> Test 2 smooth and preonly is not OK
> zhaowenbo at ubuntu:~/test_slepc/SPARK/spark$ make NCORE=1 runkr_smooth
> mpirun -n 1 ./step-41 \
>    -st_ksp_type gmres -st_ksp_view -st_ksp_monitor  \
>    -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 1 \
>    -st_ksp_view  -mata AMAT.dat -matb BMAT.dat \
>    -st_mg_coarse_ksp_type preonly   -st_mg_coarse_ksp_monitor  \
>    -eps_nev 1 -eps_ncv 10  -eps_monitor -log_view > log_smooth 2>&1
> makefile:43: recipe for target 'runkr_smooth' failed
> make: *** [runkr_smooth] Error 91
>
> Test 3 nonsmooth and gmres is not OK
> zhaowenbo at ubuntu:~/test_slepc/SPARK/spark$ make NCORE=1 runkr_gmres
> mpirun -n 1 ./step-41 \
>    -st_ksp_type gmres  -st_ksp_view -st_ksp_monitor  \
>    -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 0 \
>    -st_ksp_view  -mata AMAT.dat -matb BMAT.dat \
>    -st_mg_coarse_ksp_type gmres  -st_mg_coarse_ksp_monitor
> -st_mg_coarse_ksp_rtol 1.0e-6 \
>

DO NOT DO THIS. Please send the output where you do NOTHING to the coarse
solver.

  Thanks,

     Matt


>    -eps_nev 1 -eps_ncv 10  -eps_monitor  -log_view > log_gmres 2>&1
> makefile:59: recipe for target 'runkr_gmres' failed
> make: *** [runkr_gmres] Error 91
>
> log-files is attached.
>
>
> You mentioned that B is not symmetric. I assume it is elliptic
>> (diffusion). Where does the asymmetry come from?
>>
>>
> It is a two-group diffusion equations, where group denotes neutron enegry
> discretisation.
> Matrix B consists of neutron diffusion/leakage term, removal term and
> minus neutron scatter source term between different energies, when matrix A
> denotes neutron fission source.
>
> Diffusion term(Laplace operator) is elliptic and symmetric. Removal term
> is diagonal only. However scatter term is asymmetry since scatter term from
> high energy to low energy is far greater than the term from low to high.
>
>
> Wenbo
>
>
>> On Mon, Oct 2, 2017 at 9:39 AM, Wenbo Zhao <zhaowenbo.npic at gmail.com>
>> wrote:
>>
>>> Matt,
>>> Thanks for your reply.
>>> For the defalt option doesnt work firstly( -st_ksp_type gmres
>>> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 1), I tried
>>> to test those options.
>>>
>>> Wenbo
>>>
>>> On Mon, Oct 2, 2017 at 9:08 PM, Matthew Knepley <knepley at gmail.com>
>>> wrote:
>>>
>>>> On Mon, Oct 2, 2017 at 8:30 AM, Wenbo Zhao <zhaowenbo.npic at gmail.com>
>>>> wrote:
>>>>
>>>>> Matt
>>>>>
>>>>> Because I am not clear about what will happen using 'preonly' for
>>>>> large scale problem.
>>>>>
>>>>
>>>> The size of the problem has nothing to do with 'preonly'. All it means
>>>> is to apply a preconditioner without a Krylov solver.
>>>>
>>>>
>>>>> It seems to use a direct solver from below,
>>>>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/
>>>>> KSP/KSPPREONLY.html
>>>>>
>>>>
>>>> However, I still cannot understand why you would change the default?
>>>>
>>>>   Matt
>>>>
>>>>
>>>>>
>>>>> Thanks!
>>>>> Wenbo
>>>>>
>>>>> On Mon, Oct 2, 2017 at 5:09 PM, Matthew Knepley <knepley at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> On Sun, Oct 1, 2017 at 9:53 PM, Wenbo Zhao <zhaowenbo.npic at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Matt,
>>>>>>> Thanks for your reply.
>>>>>>> It DOES make no sense for this problem.
>>>>>>> But I am not clear about the 'preonly' option. Which solver is used
>>>>>>> in preonly? I wonder if 'preonly' is suitable for large scale problem such
>>>>>>> as 400,000,000 unknowns.
>>>>>>> So I tried 'gmres' option and found these error messages.
>>>>>>>
>>>>>>
>>>>>> I mean, why are you setting this at all. Just do not set the coarse
>>>>>> solver. The default should work fine.
>>>>>>
>>>>>>   Thanks,
>>>>>>
>>>>>>     Matt
>>>>>>
>>>>>>
>>>>>>> Could you give me some suggestions?
>>>>>>>
>>>>>>> Thanks.
>>>>>>>
>>>>>>> Wenbo
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Oct 2, 2017 at 12:34 AM, Matthew Knepley <knepley at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> On Sun, Oct 1, 2017 at 6:49 AM, Wenbo Zhao <
>>>>>>>> zhaowenbo.npic at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> I met some questions when I use PETSC/SLEPC to solve two-group
>>>>>>>>> neutron diffusion equations with finite difference method. The grid is
>>>>>>>>> 3*3*3, when DOF on each points is 2. So the matrix size is 54*54.
>>>>>>>>> It is generalized eigenvalue problem Ax=\lamda Bx, where B is
>>>>>>>>> diagonally dominant matrix but not symmetry.
>>>>>>>>> EPS is set as below,
>>>>>>>>>  ierr = EPSSetProblemType(eps,EPS_GNHEP);CHKERRQ(ierr);¬
>>>>>>>>>  ierr = EPSSetWhichEigenpairs(eps,EPS_
>>>>>>>>> LARGEST_REAL);CHKERRQ(ierr);¬
>>>>>>>>>
>>>>>>>>> Krylovschur is used as eps sovler. GAMG is used as PC.
>>>>>>>>> I tried agg_nsmooths and mg_coarse_ksp_type. Only non-smooths and
>>>>>>>>> preonly is OK.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Why are you setting the coarse solver. This makes no sense.
>>>>>>>>
>>>>>>>>    Thanks,
>>>>>>>>
>>>>>>>>     Matt
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Test 1
>>>>>>>>> $ make NCORE=1 runkr_nonsmooth
>>>>>>>>> mpirun -n 1 ./step-41 \
>>>>>>>>>    -st_ksp_type gmres  \
>>>>>>>>>    -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths
>>>>>>>>> 0 \
>>>>>>>>>    -st_ksp_view  -mata AMAT.dat -matb BMAT.dat \
>>>>>>>>>    -st_mg_coarse_ksp_type preonly   -st_mg_coarse_ksp_monitor  \
>>>>>>>>>    -eps_nev 1 -eps_ncv 10  -eps_monitor  -log_view > log_nonsmooth
>>>>>>>>> 2>&1
>>>>>>>>>
>>>>>>>>> Test 2
>>>>>>>>> $ make NCORE=1 runkr_smooth
>>>>>>>>> mpirun -n 1 ./step-41 \
>>>>>>>>>    -st_ksp_type gmres  \
>>>>>>>>>    -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths
>>>>>>>>> 1 \
>>>>>>>>>    -st_ksp_view  -mata AMAT.dat -matb BMAT.dat \
>>>>>>>>>    -st_mg_coarse_ksp_type preonly   -st_mg_coarse_ksp_monitor  \
>>>>>>>>>    -eps_nev 1 -eps_ncv 10  -eps_monitor -log_view > log_smooth 2>&1
>>>>>>>>> makefile:43: recipe for target 'runkr_smooth' failed
>>>>>>>>> make: *** [runkr_smooth] Error 91
>>>>>>>>>
>>>>>>>>> Test 3
>>>>>>>>> $ make NCORE=1 runkr_gmres
>>>>>>>>> mpirun -n 1 ./step-41 \
>>>>>>>>>    -st_ksp_type gmres  \
>>>>>>>>>    -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths
>>>>>>>>> 0 \
>>>>>>>>>    -st_ksp_view  -mata AMAT.dat -matb BMAT.dat \
>>>>>>>>>    -st_mg_coarse_ksp_type gmres  -st_mg_coarse_ksp_monitor
>>>>>>>>> -st_mg_coarse_ksp_rtol 1.0e-6 \
>>>>>>>>>    -eps_nev 1 -eps_ncv 10  -eps_monitor  -log_view > log_gmres 2>&1
>>>>>>>>> makefile:59: recipe for target 'runkr_gmres' failed
>>>>>>>>> make: *** [runkr_gmres] Error 91
>>>>>>>>>
>>>>>>>>> Log files were attched.
>>>>>>>>> The matrix file were also attched as AMAT.dat and BMAT.dat.
>>>>>>>>>
>>>>>>>>> Is it correct? Or something wrong with my code or commad-line?
>>>>>>>>>
>>>>>>>>> Thanks!
>>>>>>>>>
>>>>>>>>> Wenbo
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> What most experimenters take for granted before they begin their
>>>>>>>> experiments is infinitely more interesting than any results to which their
>>>>>>>> experiments lead.
>>>>>>>> -- Norbert Wiener
>>>>>>>>
>>>>>>>> https://www.cse.buffalo.edu/~knepley/
>>>>>>>> <http://www.caam.rice.edu/%7Emk51/>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> What most experimenters take for granted before they begin their
>>>>>> experiments is infinitely more interesting than any results to which their
>>>>>> experiments lead.
>>>>>> -- Norbert Wiener
>>>>>>
>>>>>> https://www.cse.buffalo.edu/~knepley/
>>>>>> <http://www.caam.rice.edu/%7Emk51/>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> What most experimenters take for granted before they begin their
>>>> experiments is infinitely more interesting than any results to which their
>>>> experiments lead.
>>>> -- Norbert Wiener
>>>>
>>>> https://www.cse.buffalo.edu/~knepley/
>>>> <http://www.caam.rice.edu/%7Emk51/>
>>>>
>>>
>>>
>>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
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