Compilation errors due to fixed typs in deal.II

[jh66637]

Explicitly using double for interface coupling results in compilation errors after the fixture of types in deal.II dealii/dealii#14142.

The decision to use double instead of Number is related due to the design choice to keep Number out of BoundaryDescriptors.

I might find some time to work on this towards the end of the week.

[peterrum]

A minimal test:

#include <deal.II/matrix_free/fe_point_evaluation.h>

using namespace dealii;

template <int n_components, int dim, int spacedim, typename Number>
void
test()
{
  std::unique_ptr<Mapping<dim, spacedim>>       mapping;
  std::unique_ptr<FiniteElement<dim, spacedim>> fe;

  FEPointEvaluation<n_components, dim, spacedim, Number> fpe(
    *mapping, *fe, UpdateFlags::update_default);

  Triangulation<dim, spacedim> tria;

  fpe.reinit(tria.begin(), ArrayView<const Point<dim>>());

  fpe.evaluate(ArrayView<const Number>(), EvaluationFlags::values);

  fpe.integrate(ArrayView<Number>(), EvaluationFlags::values);
}

int
main()
{
  test<1, 1, 1, double>();
  test<2, 1, 1, double>();

  test<1, 2, 2, double>();
  test<2, 2, 2, double>();
  test<3, 2, 2, double>();

  test<1, 3, 3, double>();
  test<2, 3, 3, double>();
  test<3, 3, 3, double>();
  test<4, 3, 3, double>();

  test<1, 1, 1, float>();
  test<2, 1, 1, float>();

  test<1, 2, 2, float>();
  //test<2, 2, 2, float>(); // not working 
  test<3, 2, 2, float>();

  test<1, 3, 3, float>();
  test<2, 3, 3, float>();
  //test<3, 3, 3, float>(); // not working
  test<4, 3, 3, float>();
}

[peterrum]

This should fix it:

diff --git a/include/deal.II/base/derivative_form.h b/include/deal.II/base/derivative_form.h
index 10d6545..ba4985b 100644
--- a/include/deal.II/base/derivative_form.h
+++ b/include/deal.II/base/derivative_form.h
@@ -108,12 +108,14 @@ public:
    * Number>. In particular, if order == 1 and the derivative is the Jacobian of
    * $\mathbf F(\mathbf x)$, then Tensor[i] = $\nabla F_i(\mathbf x)$.
    */
-  operator Tensor<order + 1, dim, Number>() const;
+  template<typename Number2>
+  operator Tensor<order + 1, dim, Number2>() const;
 
   /**
    * Converts a DerivativeForm<1, dim, 1, Number> to Tensor<1, dim, Number>.
    */
-  operator Tensor<1, dim, Number>() const;
+   template<typename Number2>
+  operator Tensor<1, dim, Number2>() const;
 
   /**
    * Return the transpose of a rectangular DerivativeForm,
@@ -273,8 +275,9 @@ DerivativeForm<order, dim, spacedim, Number>::operator[](
 
 
 template <int order, int dim, int spacedim, typename Number>
+template<typename Number2>
 inline DerivativeForm<order, dim, spacedim, Number>::
-operator Tensor<1, dim, Number>() const
+operator Tensor<1, dim, Number2>() const
 {
   Assert((1 == spacedim) && (order == 1),
          ExcMessage("Only allowed for spacedim==1."));
@@ -285,8 +288,9 @@ operator Tensor<1, dim, Number>() const
 
 
 template <int order, int dim, int spacedim, typename Number>
+template<typename Number2>
 inline DerivativeForm<order, dim, spacedim, Number>::
-operator Tensor<order + 1, dim, Number>() const
+operator Tensor<order + 1, dim, Number2>() const
 {
   Assert((dim == spacedim), ExcMessage("Only allowed when dim==spacedim."));

I'll open a PR in deal.II later today.

[jh66637]

Thank you :)

[jh66637]

Merging this: #257 (comment), the pipeline is successful, and the Issue can be closed.

[nfehn]

should be resolved by dealii/dealii#14159