Hello,
While changing the boundary conditions for a Darcy problem (practically
equivalent to step-20) , I encountered an InternalError. The culprit is
VectorTools::computer_no_normal_flux_constraints, which states
'unit_support_points.size() == fe_collection[i].dofs_per_face' (complete
message, see below).
After a bit of digging, I think the following happens. The basis for the
problem is a system of RaviarThomas + DGQ. The RaviarThomas element has no
support points, but has dofs_per_face. Therefore the same applies to the
FESystem, which therefore triggers the above mentioned error.
To reproduce, make a copy of step 20, include
<deal.II/lac/constraint_matrix.h> and add at the end of make_grid_and_dofs
the following
std::set<types::boundary_id> boundary_ids;
ConstraintMatrix constraints;
VectorTools::compute_no_normal_flux_constraints(
dof_handler,
0,
boundary_ids,
constraints
);
Let me know if you need more information,
Lars Corbijn
The complete error message:
An error occurred in line <5270> of file
</home/lars/AUR/deal-ii/src/dealii-8.4.2/include/deal.II/numerics/vector_tools.templates.h>
in function
void dealii::VectorTools::compute_nonzero_normal_flux_constraints(const
DoFHandlerType<dim, spacedim>&, unsigned int, const std::set<unsigned
char>&, typename dealii::FunctionMap<spacedim>::type&,
dealii::ConstraintMatrix&, const dealii::Mapping<dim, spacedim>&) [with int
dim = 2; DoFHandlerType = dealii::DoFHandler; int spacedim = 2; typename
dealii::FunctionMap<spacedim>::type = std::map<unsigned char, const
dealii::Function<2, double>*, std::less<unsigned char>,
std::allocator<std::pair<const unsigned char, const dealii::Function<2,
double>*> > >]
The violated condition was:
unit_support_points.size() == fe_collection[i].dofs_per_face
The name and call sequence of the exception was:
ExcInternalError()
Additional Information:
This exception -- which is used in many places in the library -- usually
indicates that some condition which the author of the code thought must be
satisfied at a certain point in an algorithm, is not fulfilled. An example
would be that the first part of an algorithm sorts elements of an array in
ascending order, and a second part of the algorithm later encounters an an
element that is not larger than the previous one.
There is usually not very much you can do if you encounter such an
exception since it indicates an error in deal.II, not in your own program.
Try to come up with the smallest possible program that still demonstrates
the error and contact the deal.II mailing lists with it to obtain help.
Stacktrace:
-----------
#0 /usr/lib/libdeal_II.g.so.8.4.2: void
dealii::VectorTools::compute_nonzero_normal_flux_constraints<2,
dealii::DoFHandler, 2>(dealii::DoFHandler<2, 2> const&, unsigned int,
std::set<unsigned char, std::less<unsigned char>, std::allocator<unsigned
char> > const&, dealii::FunctionMap<2, double>::type&,
dealii::ConstraintMatrix&, dealii::Mapping<2, 2> const&)
#1 /usr/lib/libdeal_II.g.so.8.4.2: void
dealii::VectorTools::compute_no_normal_flux_constraints<2,
dealii::DoFHandler, 2>(dealii::DoFHandler<2, 2> const&, unsigned int,
std::set<unsigned char, std::less<unsigned char>, std::allocator<unsigned
char> > const&, dealii::ConstraintMatrix&, dealii::Mapping<2, 2> const&)
#2 ./step-20: Step20::MixedLaplaceProblem<2>::make_grid_and_dofs()
#3 ./step-20: Step20::MixedLaplaceProblem<2>::run()
#4 ./step-20: main
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