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Re: [Getfem-users] Bug? in enumerating DOFs on region and faces
From: |
Yves Renard |
Subject: |
Re: [Getfem-users] Bug? in enumerating DOFs on region and faces |
Date: |
Mon, 19 Jul 2010 11:04:19 +0200 |
User-agent: |
KMail/1.13.2 (Linux/2.6.32-22-server; KDE/4.4.2; x86_64; ; ) |
Dear Roman,
The policy for which a dof is on a face or not is rather clear : A dof should
be declared on a face if the corresponding shape function is nonzero on that
face.
Surprisingly, the belonging on faces of the derivative dof of the segment
hermite element was explicitely disabled (getfem_fem.cc lines 1471 and 1477).
This was not correct, of course and I don't remember why it is so !
Thank you for this bug report !
Yves.
On vendredi 16 juillet 2010, Roman Putanowicz wrote:
> Dear Yves,
>
> I think I have found a bug in accessing DOFs on regions and faces.
>
> The setup is as follows : single segment mesh with HERMITE fem.
> I create two mesh regions (for the left end node and for the right end
> node).
>
> The output of the demo program (sent in attachment) is as follows:
>
> -----------------------------------
> $ ./dofs_of_region
> DOFs on the left end : [0]
> DOFs on the right end : [2]
> DOFs on convex : 0 1 2 3
> DOFs on face 0 of convex : 2
> DOFs on face 1 of convex 0
> -----------------------------------
>
> DOFs on convex are listed properly as 0 1 2 3.
> I would expect DOFs on left end region as well as dofs on face 1 of the
> convex to be [0,1] and not just [0]. So it seems that the dofs for
> derivative degrees of freedom are missing.
>
> I have looked at code for dal::bit_vector mesh_fem::basic_dof_on_region()
> but I do not see there provision for non-Lagrangian elements.
>
> I can check if the fem of a convex is Lagrangian but what should be done
> if it is not?
>
> I am afraid that this can be a little pandora box :( but hope that this is
> not) (in particular I have in mind the code for setting Dirichlet boundary
> condition on Hermite elements).
>
> In attachment there is mentioned test code to reproduce the bug.
>
> Regards
>
> Roman
--
Yves Renard (address@hidden) tel : (33) 04.72.43.87.08
Pole de Mathematiques, INSA-Lyon fax : (33) 04.72.43.85.29
20, rue Albert Einstein
69621 Villeurbanne Cedex, FRANCE
http://math.univ-lyon1.fr/~renard
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