[petsc-users] why a certain option cannot be used
Dave May
dave.mayhem23 at gmail.com
Wed Jul 16 17:11:40 CDT 2014
To see all the fieldsplit options, run with
./ex70 -pc_type fieldsplit -help
-help will only display the options relevant to the current configuration
of your KSP and PC.
On 17 July 2014 00:10, Dave May <dave.mayhem23 at gmail.com> wrote:
> Run with
> -help
>
>
> On 17 July 2014 00:07, Sun, Hui <hus003 at ucsd.edu> wrote:
>
>> Thank you Dave, it does solve the problem. Another question is: since
>> some options like
>>
>> -fieldsplit_0_pc_type
>>
>> does not show up if I type
>>
>> ./ex70 -help
>>
>> how then can I have a complete list of all the options?
>>
>> Best,
>> Hui
>>
>>
>> ------------------------------
>> *From:* Dave May [dave.mayhem23 at gmail.com]
>> *Sent:* Wednesday, July 16, 2014 2:57 PM
>> *To:* Sun, Hui
>> *Cc:* Matthew Knepley; petsc-users at mcs.anl.gov
>>
>> *Subject:* Re: [petsc-users] why a certain option cannot be used
>>
>> You need to specify on the command line
>> -pc_type fieldsplit -fieldsplit_0_pc_type xxx -fieldsplit_1_pc_type yyy
>>
>> Where xxx and yyy are the desired preconditioners for the (1,1) block
>> and (2,2) block. Note that the default PC (ilu(0)) applied to both splits
>> will fail for this example.
>>
>> The comments in the code are misleading and incorrect. Without the
>> option -pc_type fieldsplit, all fieldsplit options have no effect.
>>
>> When debugging solvers, always run with - ksp_view (as Matt recommends)
>>
>>
>>
>> On Wednesday, 16 July 2014, Sun, Hui <hus003 at ucsd.edu> wrote:
>>
>>> No I don't think I'm using fieldsplitting although I want to use it.
>>> The output of
>>>
>>> ./ex70 -nx 32 -ny 48 -fieldsplit_1_pc_type jacobi -ksp_view
>>>
>>> is the following:
>>>
>>> KSP Object: 1 MPI processes
>>>
>>> type: gmres
>>>
>>> GMRES: restart=30, using Classical (unmodified) Gram-Schmidt
>>> Orthogonalization with no iterative refinement
>>>
>>> GMRES: happy breakdown tolerance 1e-30
>>>
>>> maximum iterations=10000, initial guess is zero
>>>
>>> tolerances: relative=1e-05, absolute=1e-50, divergence=10000
>>>
>>> left preconditioning
>>>
>>> using PRECONDITIONED norm type for convergence test
>>>
>>> PC Object: 1 MPI processes
>>>
>>> type: none
>>>
>>> linear system matrix = precond matrix:
>>>
>>> Matrix Object: 1 MPI processes
>>>
>>> type: nest
>>>
>>> rows=4608, cols=4608
>>>
>>> Matrix object:
>>>
>>> type=nest, rows=2, cols=2
>>>
>>> MatNest structure:
>>>
>>> (0,0) : prefix="a00_", type=mpiaij, rows=3072, cols=3072
>>>
>>> (0,1) : prefix="a01_", type=mpiaij, rows=3072, cols=1536
>>>
>>> (1,0) : prefix="a10_", type=mpiaij, rows=1536, cols=3072
>>>
>>> (1,1) : prefix="a11_", type=mpiaij, rows=1536, cols=1536
>>>
>>> residual u = 2.6315e-05
>>>
>>> residual p = 0.000229872
>>>
>>> residual [u,p] = 0.000231373
>>>
>>> discretization error u = 0.00633503
>>>
>>> discretization error p = 0.121534
>>>
>>> discretization error [u,p] = 0.121699
>>>
>>> WARNING! There are options you set that were not used!
>>>
>>> WARNING! could be spelling mistake, etc!
>>>
>>> Option left: name:-fieldsplit_1_pc_type value: jacobi
>>>
>>>
>>> ------------------------------
>>> *From:* Sun, Hui
>>> *Sent:* Wednesday, July 16, 2014 2:40 PM
>>> *To:* Matthew Knepley
>>> *Cc:* petsc-users at mcs.anl.gov <http://UrlBlockedError.aspx>
>>> *Subject:* RE: [petsc-users] why a certain option cannot be used
>>>
>>> Thank you Matt. I've corrected it to
>>>
>>> ./ex70 -nx 32 -ny 48 -fieldsplit_1_pc_type jacobi
>>>
>>>
>>> However the output is still:
>>>
>>>
>>> residual u = 2.6315e-05
>>>
>>> residual p = 0.000229872
>>>
>>> residual [u,p] = 0.000231373
>>>
>>> discretization error u = 0.00633503
>>>
>>> discretization error p = 0.121534
>>>
>>> discretization error [u,p] = 0.121699
>>>
>>> WARNING! There are options you set that were not used!
>>>
>>> WARNING! could be spelling mistake, etc!
>>>
>>> Option left: name:-fieldsplit_1_pc_type value: jacobi
>>>
>>>
>>> If I type
>>>
>>>
>>> ./ex70 -help | grep fieldsplit_1_
>>>
>>>
>>> the output is that nothing coming out.
>>>
>>>
>>>
>>>
>>>
>>> ------------------------------
>>> *From:* Matthew Knepley [knepley at gmail.com <http://UrlBlockedError.aspx>
>>> ]
>>> *Sent:* Wednesday, July 16, 2014 2:32 PM
>>> *To:* Sun, Hui
>>> *Cc:* petsc-users at mcs.anl.gov <http://UrlBlockedError.aspx>
>>> *Subject:* Re: [petsc-users] why a certain option cannot be used
>>>
>>> On Wed, Jul 16, 2014 at 4:25 PM, Matthew Knepley <knepley at gmail.com
>>> <http://UrlBlockedError.aspx>> wrote:
>>>
>>>> On Wed, Jul 16, 2014 at 4:22 PM, Sun, Hui <hus003 at ucsd.edu
>>>> <http://UrlBlockedError.aspx>> wrote:
>>>>
>>>>> Thank you Matt for answering, however even with that I don't think
>>>>> it works. For example, the command
>>>>>
>>>>> ./ex70 -nx 32 -ny 48 -fieldsplit_1_type jacobi
>>>>>
>>>>
>>>> You have mistyped. Look carefully at my last message:
>>>>
>>>> -fieldsplit_1_pc_type jacobi
>>>>
>>>
>>> I also want to note that you can see all the available options with
>>> -help. It does produce
>>> a lot of output, but you can segregate it by prefix ("fieldsplit_1_").
>>> You can also see the
>>> prefix of each solver component using -ksp_view.
>>>
>>> Matt
>>>
>>>
>>>> Matt
>>>>
>>>>
>>>>> gives me the following output
>>>>>
>>>>>
>>>>> residual u = 2.6315e-05
>>>>>
>>>>> residual p = 0.000229872
>>>>>
>>>>> residual [u,p] = 0.000231373
>>>>>
>>>>> discretization error u = 0.00633503
>>>>>
>>>>> discretization error p = 0.121534
>>>>>
>>>>> discretization error [u,p] = 0.121699
>>>>>
>>>>> WARNING! There are options you set that were not used!
>>>>>
>>>>> WARNING! could be spelling mistake, etc!
>>>>>
>>>>> Option left: name:-fieldsplit_1_type value: jacobi
>>>>>
>>>>>
>>>>> Furthermore, if I look into the possible options with keyword
>>>>> fieldsplit involved by the command:
>>>>>
>>>>>
>>>>> ./ex70 -help | grep -A5 fieldsplit
>>>>>
>>>>>
>>>>> I get this output:
>>>>>
>>>>>
>>>>> eisenstat ilu icc cholesky asm gasm ksp composite redundant nn mat
>>>>> fieldsplit galerkin exotic hmpi asa cp lsc redistribute svd gamg tfs
>>>>> (PCSetType)
>>>>>
>>>>> -pc_use_amat: <FALSE> use Amat (instead of Pmat) to define
>>>>> preconditioner in nested inner solves (PCSetUseAmat)
>>>>>
>>>>> Krylov Method (KSP) options
>>>>> -------------------------------------------------
>>>>>
>>>>> -ksp_type <gmres>: Krylov method (one of) cg groppcg pipecg cgne
>>>>> nash stcg gltr richardson
>>>>>
>>>>> chebyshev gmres tcqmr bcgs ibcgs fbcgs fbcgsr bcgsl cgs tfqmr cr
>>>>> pipecr lsqr preonly qcg bicg fgmres minres symmlq lgmres lcd gcr pgmres
>>>>> specest dgmres (KSPSetType)
>>>>>
>>>>> -ksp_max_it <10000>: Maximum number of iterations (KSPSetTolerances)
>>>>>
>>>>>
>>>>> So I don't see any option that's similar to -fieldsplit_1_type.
>>>>>
>>>>>
>>>>> Hui
>>>>>
>>>>>
>>>>>
>>>>> ------------------------------
>>>>> *From:* Matthew Knepley [knepley at gmail.com
>>>>> <http://UrlBlockedError.aspx>]
>>>>> *Sent:* Wednesday, July 16, 2014 2:16 PM
>>>>> *To:* Sun, Hui
>>>>> *Cc:* petsc-users at mcs.anl.gov <http://UrlBlockedError.aspx>
>>>>> *Subject:* Re: [petsc-users] why a certain option cannot be used
>>>>>
>>>>> On Wed, Jul 16, 2014 at 4:09 PM, Sun, Hui <hus003 at ucsd.edu
>>>>> <http://UrlBlockedError.aspx>> wrote:
>>>>>
>>>>>> I want to solve Stokes equation using user defined schur complement
>>>>>> preconditioner. So I'm reading and testing snes/examples/tutorial/ex55.c,
>>>>>> and ex70.c. In these examples, there are comments about the usage, for
>>>>>> example:
>>>>>>
>>>>>> mpiexec -n 2 ./stokes -nx 32 -ny 48 -fieldsplit_1_user_pc.
>>>>>>
>>>>>> However the option -fieldsplit_1_user_pc is not recognized by the
>>>>>> executable. The output of the above command is:
>>>>>>
>>>>>
>>>>> This ("user_pc") is just a mnemonic. What it means is that you can
>>>>> use any PC in this slot. What he should have written is
>>>>>
>>>>> -fieldsplit_1_pc_type <user pc>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Matt
>>>>>
>>>>>
>>>>>> residual u = 2.6315e-05
>>>>>>
>>>>>> residual p = 0.000229872
>>>>>>
>>>>>> residual [u,p] = 0.000231373
>>>>>>
>>>>>> discretization error u = 0.00633503
>>>>>>
>>>>>> discretization error p = 0.121534
>>>>>>
>>>>>> discretization error [u,p] = 0.121699
>>>>>>
>>>>>> WARNING! There are options you set that were not used!
>>>>>>
>>>>>> WARNING! could be spelling mistake, etc!
>>>>>>
>>>>>> Option left: name:-fieldsplit_1_user_pc (no value)
>>>>>>
>>>>>>
>>>>>> I'm wondering what's going on. Is that because I need some specific
>>>>>> options during my configuring of the package? By the way, the version of
>>>>>> PETSc I'm using is 3.4.4.
>>>>>>
>>>>>>
>>>>>> Best,
>>>>>>
>>>>>> Hui
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> 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
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> 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
>>>>
>>>
>>>
>>>
>>> --
>>> 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
>>>
>>
>
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