[Dune] dune-alugrid: Assertion `DetDf > 0' failed

[Andreas Dedner]

Hi.
The determinant in the alugrid TrilinearMapping class where the
assertion is triggered, is used to compute for example the integration
element or the volume of the cells in the grid. Alugrid assumes a
certain orientation of the grid elements (determinant > 0). I would have
thought that would be checked during the grid generation process and the
elements local vertex numbering changed if necessary but you might have
found a bad case here. I would need (at least):
0) which alugrid type are you using, e.g., Cube<3> or Cube<2,3> or...
1) the value of detDf (is it zero or negative)
2) the call stack for the error
3) The class also contains a variable 'a' which describes the mapping
   and can be used to figure out which element in your dgf file is
   causing the problem
4) If that doesn't work then the dgf file...
Andreas


On 12/11/15 17:11, Jelena Grižić wrote:
> Dear all,
> 
> 
> while constructing mesh from dgf file, I receive message :
> 
> dune-alugrid/dune/alugrid/3d/mappings_imp.cc:187: Dune::alu3d_ctype
> Dune::TrilinearMapping::det(const coord_t&): Assertion `DetDf > 0' failed.
> 
> Could you explain what that exactly means and what could be problem with
> my mesh?
> 
> Unfortunately, dgf file is to big (56,7 MB) to be included in mail.
> 
> 
> Thank you.
> 
> Best regards,
> 
> Jelena Grižić
> 
> 
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