Re: [Libmesh-devel] Read in GMV files

[Derek G. <fri...@gm...>]

John,

Sorry to dredge up an old email... but I'm wondering if you have any
idea how much error there is in this process?  Are the full double
precision numbers being output to the GMV file and read back in?

I'm trying to re-use some runs I made last year... I have xda's for
the mesh, and xdr's for the solutions... but for whatever reason those
xdr's are corrupt (I remember that they were corrupt when they first
came out too...).  I also have gmv's and plt's of the same junk.  I
would _love_ to re-use these solutions as they are on millions of
elements (took a long time to get, even on lonestar).  But I'm going
to be using them to drive error and indicator calculations so I need
them to be precise.

Thanks,
Derek

On 6/5/07, John Peterson <pet...@cf...> wrote:
> Hi,
>
> It's possible to read in a GMV file and solutions.
> Sample code:
>
> {
>   Mesh mesh(dim);
>   GMVIO gmvio(mesh);
>   gmvio.read("meshfile.gmv");
> }
>
> If there were solution fields in the GMV file they
> were read in as well and are now stored in the GMV
> object.  Suppose you later created an EquationSystems
> object based on this mesh:
>
> {
>   EquationSystems es(mesh);
>
>   TransientLinearImplicitSystem & heat_system =
>    es.add_system<TransientLinearImplicitSystem> ("HeatSystem");
>
>   heat_system.add_variable ("T", FIRST);
>
>   es.init();
> }
>
> Then, you can copy the solution you read in
> from the GMV file to the EquationSystems object:
>
> {
>   gmvio.copy_nodal_solution(es);
> }
>
> I did it in stages like this because you can't initialize the
> EquationSystems without the mesh, and you can't easily put the
> solution data into the EquationSystems object before it has been
> initialized.
>
> Note that there isn't much information stored in a GMV file: only
> nodal (or cell, which I didn't support yet) data values, so this
> feature is limited to reading in linear, Lagrange elements (sorry
> Roy!).
>
> If you wrote out a quadratic solution to a GMV file, it was probably
> written out as linear sub-elements, so this is what will be read back
> in, not your nice original quadratic solution.  It will also probably
> completely break on non-conforming (AMR) GMV files, I haven't even
> tested that yet.
>
> I mainly wrote this was to be able to post-process uniform GMV files
> for which I forgot to also write out the xda files.  I hope it will
> be useful for that, and maybe other stuff.
>
> -John
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by DB2 Express
> Download DB2 Express C - the FREE version of DB2 express and take
> control of your XML. No limits. Just data. Click to get it now.
> http://sourceforge.net/powerbar/db2/
> _______________________________________________
> Libmesh-devel mailing list
> Lib...@li...
> https://lists.sourceforge.net/lists/listinfo/libmesh-devel
>