SNESSetUp() and matrix-free options

[Lisandro Dalcin]

Well, it was not so easy to change the options name...

We would need to update docs, tests, tutorial examples, and at this
point it is not clear if we could agree on better options names...

I'm now following a different approach, hope the diff attached make it
clear enough... Just take a look to changes to SNESSetFromOptions()

-


On Thu, May 7, 2009 at 10:26 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>  How about?
>
>  -snes_mf   (means what it currently means)
>
>  -snes_mf operator (means what -snes_mf_operator means)
>
>   Barry
>
> On May 7, 2009, at 6:03 PM, Lisandro Dalcin wrote:
>
>> On Thu, May 7, 2009 at 6:14 PM, Jed Brown <jed at 59a2.org> wrote:
>>>
>>> Barry Smith wrote:
>>>>
>>>>   I understand this. I just don't view this as a big deal worth
>>>> changing the code over.
>>>
>>> I agree.  My comment was that *if* the options were to be changed, as
>>> Lisandro was suggesting, then it would be better to eliminate
>>> unnecessary options conflicts.
>>>
>>
>> Well, now that I'm actually writing the code, things are a bit more
>> clear...
>>
>> perhaps we should have just two options
>>
>> 1) -snes_mf, if passed, should be string "full" or "operator" (not
>> sure about these)
>> 2) -snes_mf_version, if passed, should be integer 1 or 2
>>
>> In Python pseudocode (thinking options like a Python dict)
>>
>>
>> if "snes_mf" in options:
>>
>>  version = options.get("snes_mf_version", 1)
>>  if version == 1:
>>     MatCreateSNESMF(...)
>>  elif version == 2:
>>     SNESDefaultMatrixFreeCreate2(...)
>>  else:
>>     raise PetscError
>>
>>  value = options["snes_mf"]
>>  if value == "operator":
>>     SNESSetJacobian(J,0,0,...)
>>  elif value == "full":
>>     SNESSetJacobian(J,J,MatMFFDComputeJacobian)
>>  else:
>>     raise PetscError
>>
>>
>> Note that I expect snes_mf_version=2 (despite being MatShell based) to
>> work with snes_mf="operator"
>>
>> What do you think?
>>
>> --
>> Lisandro Dalcín
>> ---------------
>> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
>> Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
>> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
>> PTLC - Güemes 3450, (3000) Santa Fe, Argentina
>> Tel/Fax: +54-(0)342-451.1594
>
>



-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594
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