dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

On 09/02/11 22:43, Anders Logg wrote:
> On Wed, Feb 09, 2011 at 10:11:40AM -0800, Johan Hake wrote:
>> Hello!
>>
>> I am pretty sure the reason the Macbot still complains (mesh unit test) is
>> that refine is broken for SWIG 2.0.
>>
>> I think it is some premature destruction of a refined mesh. I would suggest we
>> implement a full shared_ptr version of the interface to get around this
>> problem. I have no clue of why it works for SWIG 1.3.40. Probably because a
>> faulty implementation.
>>
>> I also suggest more developers upgrade to SWIG 2.0.1 and maybe one of the
>> linux build bots two? If it is only the Macbot that uses SWIG 2.0 it is easily
>> to think it is some Mac specific error.
>>
>> Johan
> 
> I plan to merge with main tomorrow if my buildbot is green. Then Marie
> also needs to merge (we have both touched refine.h/cpp). Then we can
> sort out the shared_ptrs.
> 

I really don't get the approach to hierarchies. Mesh refinement was
simple, and now something simple has become complex (with bugs that are
hard to track down because of the introduced complexity).

This hierarchy business looks viral - now I get Swig warnings for
DirichleBC.

I would much rather keep basic classes simple, and have hierarchical
containers that can keep track of parent/child relationships. The
present approach seems to take a narrow/immediate view on the issue.

Garth

> I've been working on a new (old) refinement algorithm which instead of
> bisection divides marked triangles into 4 triangles, then fixes the
> neighbors. It's sometimes a better option since fewer refinements are
> needed and it guarantees that all edges of marked triangles will be
> split during refinement.
> 
> We had this a while back but it was removed since it relied heavily on
> parent-child relationships between the individual cells and vertices
> of the mesh. We don't have that anymore (only between the meshes).
> 
> It's currently only implemented in 2D and can be enabled with the
> global option "refinement_algoritm" set to "regular_cut". The default
> value is "recursive_bisection". There are some other options that I
> plan to remove since they don't work and are presumably not as good as
> "recursive_bisection". In the near future, we will need to
> remove/reimplement both algorithms to work in parallel, or (ideally)
> wrap an external library that provides parallel mesh refinement (like
> MAdLib). Niclas has some parallel mesh refinement but I don't know if
> there are any plans to merge it into DOLFIN.
> 
> --
> Anders
> 
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