[Dune] Tree structure of the grid and binary search

[Martin Nolte]

Hi Andrea,

1) The element (entity of codimension 0) provides a hierarchic iterator. This 
allows you to traverse all its children up to a maximal level 
(entity.level()+1 in your case).

2) It is my understanding that you cannot coarsen away macro entities. 
Therefore, the grid will contain exactly the same macro entities are before 
the adaptation. This holds for all elements with satisfying "!mightVanish()".

If an entity is present in the grid before and after the adaptation, it has to 
keep its id (both, local and global). Otherwise, there are no constraints that 
I am aware of.

Some questions to the developers:
(a) Should the level-0 index set be kept static over adaptation?
(b) May the grid change the geometric realization of a retained entity?
(c) May the grid change the orientation of a retained entity (twist)?
(d) May a copy of an entity have a different orientation?
For (a), we could also add a capability.

Best,

Martin

On 06/14/2013 03:53 PM, Sacconi, Andrea wrote:
> Hello everyone,
>
> I have a couple of questions concerning the grid:
>
> 1) suppose you have to implement a binary search of your grid. How can you get
> access from a given element (at a given level) to the children
> (_only_the_children) it has on the subsequent level? I tried to play with
> levelView or similar things, but I didn't get an answer.
> 2) if you have an initial macro-triangulation and you adapt the grid
> (performing both coarsening and refining), what happens to the tree structure?
> What about the levels of the new grid? Is there some kind of relation between
> the new grid elements and the level-0 elements of the grid, prior to the
> adapting phase?
>
> Thanks for your kind help!
>
> Andrea
> __________________________________________________________
>
> Andrea Sacconi
> PhD student, Applied Mathematics
> AMMP Section, Department of Mathematics, Imperial College London,
> London SW7 2AZ, UK
> a.sacconi11 at imperial.ac.uk
>
>
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-- 
Dr. Martin Nolte <nolte at mathematik.uni-freiburg.de>

Universität Freiburg                                   phone: +49-761-203-5630
Abteilung für angewandte Mathematik                    fax:   +49-761-203-5632
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