petsc and x-fem

[Barry Smith]

    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