On 8/3/23 04:54, 'Jost Arndt' via deal.II User Group wrote:
for (unsigned int f = 0; f < GeometryInfo<dim>::faces_per_cell; ++f)
{
if
(cell->face(f)->at_boundary())//(face->at_boundary())
{
std::cout << "reached line 1032" <<
std::endl;
const auto &fe_face_values =
scratch_data.reinit(cell, f);
std::cout << "reached line 1034" <<
std::endl;
/* here integration using
fe_face_value should happen*/
but the last cout never gets executed, but the code crashes. I get a long but
cryptic (to me?) stacktrace but also the following error message:
An error occurred in line <3044> of file <./source/fe/fe_values.cc> in function
dealii::FEValuesBase<dim, spacedim>::FEValuesBase(unsigned int, unsigned int,
dealii::UpdateFlags, const dealii::Mapping<dim, spacedim>&, const
dealii::FiniteElement<dim, spacedim>&) [with int dim = 2; int spacedim
= 2]
The violated condition was:
n_q_points > 0
Additional information:
There is nothing useful you can do with an FEValues object when using
a quadrature formula with zero quadrature points!
From here I am quite unsure what I did wrong or how else to create the
FEFaceValues Object? I would be really thankful about any hint!
The error likely means that MeshWorker hasn't initialized the FEFaceValues
object. Nobody knows any more how MeshWorker really works, and so we try to
discourage use of that framework. But I do know that MeshWorker allows you to
not only loop over the cells, but also the faces of a triangulation. That is
the recommended way to deal with face integrals (rather than dealing with
these face integrals as part of cell integration -- because you want to make
sure that you visit each face only once, rather than twice in your approach)
and if you tell MeshWorker that you also want to use a face worker, then it
should (?) initialize the FEFaceValues object as well.
Best
W.
--
------------------------------------------------------------------------
Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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