petsc and x-fem

[Barry Smith]

On Aug 13, 2008, at 1:50 AM, Farshid Mossaiby wrote:

> Hi,
>
> I always liked idea of a *simple* parallel FEM code in Petsc, which  
> shows most of tricks used in various programs, like parallel  
> assembly of elements and imposing Dirichlet BCs in a proper way. I  
> think this can eliminate many of "How should I do that" questions  
> from newbies like me. I think this is almost a series of copy- 
> paste's for you.
                                                                                                                                                                                                                 ^ 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    I wish :-(. I've found this to be deathly hard.


     Barry



> With a little documentation this would be a great help.
>
> Best regards,
> Farshid Mossaiby
>
>
> --- On Tue, 8/12/08, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>> From: Barry Smith <bsmith at mcs.anl.gov>
>> Subject: Re: petsc and x-fem
>> To: petsc-dev at mcs.anl.gov
>> Cc: "Techas" <techas at gmail.com>
>> Date: Tuesday, August 12, 2008, 7:48 PM
>> There is also one other example that is a lower level then
>> sieve
>> where the application more directly manages the mesh data
>> structure.
>> This is example is src/snes/examples/tutorials/ex10d. It is
>> not really
>> a complete example but gives the outline of how one can
>> write
>> such a code.
>>
>>    Barry
>>
>> On Aug 12, 2008, at 6:28 AM, Matthew Knepley wrote:
>>
>>> On Mon, Aug 4, 2008 at 6:49 AM, Techas
>> <techas at gmail.com> wrote:
>>> Hi Matthew,
>>>
>>> I'm Sergio (X-FEM), we meet some weeks ago in
>> Davis.
>>> I'm playing a little bit with petsc to evaluate
>> how much work will
>>> take me mount my x-fem code on petsc.
>>>
>>> Sorry I am just replying now. I returned from Norway
>> yesterday.
>>>
>>>
>>> My first question is: can you tell me a good example
>> of the assembly
>>> of a global finite element matrix (distributed in n
>> procs) based on a
>>> distributed mesh?
>>>
>>> The answers is in two parts. If you have a structured
>> grid, then the
>>> DA
>>> construct can do everything and is very simple. You
>> just call
>>> MatSetValuesStencil()
>>> as in KSP ex2.
>>>
>>> If you have an unstructured grid, we have new
>> functionality (only in
>>> the
>>> development version) in a Mesh object. This will be in
>> the upcoming
>>> release,
>>> but you can see it now in
>> src/dm/mesh/sieve/problems/Bratu.hh. The
>>> function
>>> to examine is Rhs_Unstructured() which forms the
>> residual for this
>>> equation
>>> on an unstructured mesh. Unfortunately, this is new
>> and has little
>>> documentation.
>>> Before the release, I will write some, but until then
>> you will have
>>> to ask me
>>> questions if you want to try it out.
>>>
>>>  Thanks,
>>>
>>>     Matt
>>>
>>>
>>> If you want me to write to the petsc list just tell
>> me.
>>>
>>> thank you!
>>> Sergio.
>>>
>>> --
>>> Sergio Zlotnik, PhD
>>> Group of Dynamics of the Lithosphere -GDL-
>>> Department of Geophysics & Tectonics
>>> Institute of Earth Sciences - CSIC
>>> Sole Sabaris s/n
>>> Barcelona 08028 - SPAIN
>>>
>>> Tel: +34 93 409 54 10
>>> Fax: +34 93 411 00 12
>>> email: szlotnik at ija.csic.es
>>>
>>> Web page http://www.ija.csic.es/gt/sergioz/
>>>
>>>
>>>
>>> -- 
>>> 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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