[Dune] inconsistency with intersection methods

[Oliver Sander]

Hi all!
I think the conditions below are reasonable, and IMHO we should try
to implement them better sooner than later.  Even though the
TwistUtility may do the trick (does it really, for all grids?),
it doesn't look like a very elegant solution to me.

In view of everybody's schedule: I do _not_ propose to comply
with Peter's conditions in 1.0.

Oliver

************************************************************************
* Oliver Sander                ** email: sander at mi.fu-berlin.de        *
* Freie Universität Berlin     ** phone: + 49 (30) 838 75217           *
* Institut für Mathematik II   ** URL  : page.mi.fu-berlin.de/~sander  *
* Arnimallee 6                 ** -------------------------------------*
* 14195 Berlin, Germany        ** Member of MATHEON (www.matheon.de)   *
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On Tue, 27 Jun 2006, Peter Bastian wrote:

> Dear Sreejith,
>
> I think you are correct that there is an inconsistency in the implementation. 
> What is necessary is the following condition:
>
> Let is be an IntersectionIterator with is.neighbor()==true and xi a point in 
> the local coordinate system of the intersection then
>
> is.intersectionSelfLocal.global(xi) == 
> is.intersectionNeighborLocal.global(xi) == is.intersectionGlobal.global(xi)
>
> This condition has also been added by Mario in the theory part of the Dune 
> paper.
>
> Question: Do we all agree on this (I do!).
>
> Best,
>
> Peter
>
>
> Sreejith Pulloor Kuttanikkad wrote:
>> Duneler,
>> 
>>  I am still not very clear on the point that when evaluating the global
>> coordinate of an intersection point from either side how one can get 
>> different global value for same point ( i think the orientation matters 
>> here.. that means one should be aware of how the orintation is defined 
>> locally.. )
>> I would assume that when finding a global coordinate of an
>> intersection point from both sides of the intersection one should get
>> the same value irrespective of orientation.
>> However when i use UG and Alberta grid i do not get the same
>> value whereas with Sgrid and Yaspgrid I get same value. I feel like
>> there is some inconsistency in the implementation of intersection methods 
>> in
>> different grids. (i dont know if i understood something wrongly)
>> 
>> thanks,
>> Sreejith
>> 
>
> -- 
> ------------------------------------------------------------------
> Peter Bastian, IWR,Uni Heidelberg, INF 348,R 020, 69120 Heidelberg
> email: Peter.Bastian at iwr.uni-heidelberg.de   Tel: +49 6221 54 4984
> WWW: http://www.iwr.uni-heidelberg.de/~Peter.Bastian Fax: ... 8860
>
>
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