[petsc-users] why a certain option cannot be used

[Matthew Knepley]

On Wed, Jul 16, 2014 at 4:40 PM, Sun, Hui <hus003 at ucsd.edu> wrote:

>  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.
>

That seems to show that you are not using PCFIELDSPLIT at all. Are you? You
can
check using -ksp_view

  Matt


>
>  ------------------------------
> *From:* Matthew Knepley [knepley at gmail.com]
> *Sent:* Wednesday, July 16, 2014 2:32 PM
>
> *To:* Sun, Hui
> *Cc:* petsc-users at mcs.anl.gov
> *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>
> wrote:
>
>>   On Wed, Jul 16, 2014 at 4:22 PM, Sun, Hui <hus003 at ucsd.edu> 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]
>>> *Sent:* Wednesday, July 16, 2014 2:16 PM
>>> *To:* Sun, Hui
>>> *Cc:* petsc-users at mcs.anl.gov
>>> *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> 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
>



-- 
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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