A better assert in FE_Q_Base::get_subface_interpolation_matrix

The previous assert checked that the element derived from FE_Q_Base
or FE_SimplexPoly. This isn't right for FE_Bernstein, which derives
from FE_Q_Base, but doesn't have support points. Instead of throwing
ExcInterpolationNotImplemented, using FE_Bernstein resulted in an
exception which was hard to understand. Change the assert so that it
checks if the incoming element has support points on the face and has
the right number of components.

diff --git a/source/fe/fe_q_base.cc b/source/fe/fe_q_base.cc
index aed10677353672f9ec1fb9ce4def70f2f257b575..10ceee4f0a410ca94aa008aeb655886e47df2547 100644 (file)
--- a/source/fe/fe_q_base.cc
+++ b/source/fe/fe_q_base.cc
@@ -632,10 +632,10 @@ FE_Q_Base<dim, spacedim>::get_subface_interpolation_matrix(
          ExcDimensionMismatch(interpolation_matrix.m(),
                               source_fe.n_dofs_per_face(face_no)));
 
-  // see if source is a Q or P element
-  if ((dynamic_cast<const FE_Q_Base<dim, spacedim> *>(&source_fe) != nullptr) ||
-      (dynamic_cast<const FE_SimplexPoly<dim, spacedim> *>(&source_fe) !=
-       nullptr))
+  Assert(source_fe.n_components() == this->n_components(),
+         ExcDimensionMismatch(source_fe.n_components(), this->n_components()));
+
+  if (source_fe.has_face_support_points(face_no))
     {
       // have this test in here since a table of size 2x0 reports its size as
       // 0x0