[Dune] Dune::IdSet

[Andreas Dedner]

1) Alugrid always has one ghost layer / no overlap
2) ids are never consecutive and ids are attached to all entities in the 
gird independent
    of their position in the hierarchy, i.e., they are unique within the 
hierarchy
3) the difference between leadIndexset and localIdSet is:
    i) the index is consecutive and only exists for leaf entities. The 
id is not
        consecutive and exists for all entites in the grid
   ii) the index can (and will) change during grid adaption and the ids 
are persistent
Andreas

Guo Hua wrote:
> Hi Oliver
>
> Thank you. I see. 
> What I want to do is to have a local id sets and global id sets only on the gridleaf.
> for the local id sets. I think using the the function leafIndexSet() is OK?
> But how to get a global id set, since I want the id should be consecutive. So globalIdSet()
> may be not OK?
>
> Cheers
> Hua
>
>
>
>
> -----Original Message-----
> From: Oliver Sander [mailto:sander at mi.fu-berlin.de]
> Sent: Mon 2/15/2010 12:15 PM
> To: Guo  Hua
> Cc: dune at dune-project.org
> Subject: Re: [Dune] Dune::IdSet
>  
> Hi Hua!
> Global ids are unique across all processors.  Local ids are unique
> only on each processor.  Hence you may have two entities on two
> different processors with the same local id.  If your programm runs
> on a single processor there is no difference.
>
> best,
> Oliver
>
> Guo Hua schrieb:
>   
>> Hi everyone
>>
>> I feel confused when reading the explanations of these two functions
>> in the class Dune::Grid< dim, dimworld, ct, GridFamily >.
>>
>> const Codim< 0 >::GlobalIdSet & globalIdSet () const
>>  	return const reference to the grids global id set
>>
>> const Codim< 0 >::LocalIdSet & localIdSet () const
>>  	return const reference to the grids local id set 
>>
>> Would you mind to make it more clear? Especially the differences of two.
>> Thanks a lot!
>>
>> Cheers,
>> Hua
>>
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>>     
>
>
>