[Dune] How to iterate over Process Boundary edges

[Aleksejs Fomins]

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Dear Martin,

Thank you very much for your reply,

This code will iterate over edges on partition type border.

I want to iterate over all edges that are shared by 2 or more processes, I call them ProcessBoundary

To be honest, I am not even sure if ProcessBoundaries are Interior or Border partition.

Could you please clarify,
Aleksejs





I am sorry if I sounded rude. I did not mean to. Just that sometimes I get replies like "read this url", which I find a bit mean.


On 10/04/15 11:18, Martin Nolte wrote:
> Hi Aleksejs,
> 
> given your introduction, I hardly dare answering. So please excuse me, if I got your question wrong of give you just another inefficient of ineffective answer.
> 
> As far as I understand your question, you seek all edges with partition type "border", so the code could look like
> 
> for( const auto &edge : edges( gridView, Partitions::interiorBorder ) )
> {
>   if( edge.partitionType() != BorderEntity )
>     continue;
> 
>   // do whatever you need to do on an edge on the process border
> }
> 
> Best,
> 
> Martin
> 
> On 04/10/2015 10:56 AM, Aleksejs Fomins wrote:
> Dear Dune,
> 
> I know I have asked this question about a hundred times now, but I would really like to get a consistent answer on it, and so far I was always sent off to read the Intersection documentation which I can probably recite with closed eyes by now.
> 
> I want to iterate over all edges that are on the process boundary and do something with them. I have a certain diagnostics routine which does only that and nothing else.
> 
> Currently employed method:
> 1.1) Iterate over all elements
> 1.2) Iterate over all intersections
> 1.3) Check if the outside element of the intersection is a Ghost
> 1.4) If yes, extract all edges associated with the intersection as subentities of the face.
> 1.5) Do sth with extracted edges
> 
> The problem with this code, disregarding the fact that it is clumsy, is also that it is very inefficient.
> Even though in my special case I am only interested in process boundary edges, this algorithm effectively iterates
> * Once over all elements,
> * twice over all faces (because all internal intersections are visited twice)
> * and twice over all process boundary edges (because most PB edges are shared by two PB faces)
> 
> So this code is approx 5 times slower than this hypothetical straightforward code
> 2.1) Iterate over all edges (entities of codim 2)
> 2.2) Find out if this edge is on a process boundary in constant time
> 2.3) If yes, do sth with this edge
> 
> The question is if it is possible to do 2.2 and if yes then how?
> 
> Regards,
> Aleksejs
>>
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> 
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