[Dune] Fwd: Re: get cell from index?

[Jö Fahlke]

Am Fr, 25. Aug 2017, 15:13:03 +0200 schrieb Gregor Corbin:
> Basically, I want to precompute an extended stencil for each cell for
> quick access to its surroundings ( more than just the direct neighbors).
> 
> So, having to search is not really an option. I also want to have as
> little storage overhead as possible. Its seems like EntitySeeds are the
> best option for me. How big are they compared to an int? And how fast is
> this grid.entity(entitySeed) method compared to a vector access?

That all depends on the grid manager.

For some grid managers, the EntitySeed will just be a single integer, for
others a bit more might be required (e.g. macro element index plus a path
through the refinement hierarchy).  Even the Entity itself would be a valid
implementation for the EntitySeed -- this isn't even a bad implementation if
the Entity is just implemented as a pointer into the internal data structures
of the grid.

Regarding speed: The EntitySeed is geared toward memory efficiency, the Entity
toward speed.  How fast it is, and how much memory is used, exactly, depends
again on which grid manager you are using.

Regards,
Jö.

-- 
Jorrit (Jö) Fahlke, Institute for Computational und Applied Mathematics,
University of Münster, Orleans-Ring 10, D-48149 Münster
Tel: +49 251 83 35146 Fax: +49 251 83 32729

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