[Dune-devel] YaspGrid becomes a tensor product grid

[Oliver Sander]

Hi Dominic,
I just had another look at your code, and cleaned up the patches a little
bit.  I was about to push the result, when I noticed a line of code that
you out-commented, saying

//TODO laesst sich auskommentieren so lange non-periodic

Does that mean that your patch introduces a regression?  Can I still use
periodic grids with your patches as they are now?

Best,
Oliver



Am 30.08.2013 15:51, schrieb Dominic Kempf:
> Dear Dune Community,
> I have spent the last weeks working on YaspGrid to make it a tensorproduct grid.
> For those of you who dont know: A tensorproduct grid is a structured
> axiparallel cube grid characterized by a coordinate vector for every
> coordinate direction. In 2D two vectors x = {x_0,...,x_s(0)} and  y =
> {y_0,...,y_s(1)} are given. The resulting grid is made of the
> following vertices: { (x_i,y_j) | i=0..s(0), j=0..s(1)}. Such grids
> are of great interest for quite a lot of people here in the Heidelberg
> DUNE community. Workarounds based on UG and GeometryGrid have been
> used that created gigantic overhead. After the release of SPGrid, Yasp
> is no longer urgently needed and was thus recoded into a
> tensorproductgrid.
> Some remarks:
> - In the backend (i.e. in the header /yaspgrid/grids.hh) the grids are
> entirely characterized by their coordinate vectors.
> - The code is completely backwards compatible. For all old
> constructors, coordinate vectors are generated. Due to the relatively
> low memory needs (in comparison to a DOF vector), this was chosen over
> a specialization of the backend code for the equidistant case. Should
> extensive performance testing show, that this is a problem, this will
> be implemented.
> - The data structure to be used to give coordinates to the constructor
> of YaspGrid is Dune::array<std::vector<ctype>, dim>. Helper classes to
> generate such vectors with sequences such as geometric series are to
> follow, but not part of this first release.
> - As a side effect, YaspGrid is no longer tied to having a trivial origin!
> - While digging through the backend code, I realized a lot of
> redundant code or code that is actually never used. Such things have
> not been tackled yet.
>
> Unfortunately implementation is not yet done completely. The following
> features are NOT yet fully implemented:
> - periodic grids
> - the refinement option choosing to keep the overlap in cell size,
> instead of physical size.
>
> I invite everybody to take a look at my work and test it. You find the
> feature branch on my github account:
> https://github.com/dokempf/dune-grid/tree/feature/tensorproductgrid
>
> I will not be available to work on this until around mid of november,
> but until then, I would like to collect your feedback and wishes to
> make the new YaspGrid first choice for problems that require a
> tensorproduct grid.
>
> Best regards,
> Dominic Kempf
>
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