fix description of simplex test step-23

diff --git a/tests/simplex/step-23.cc b/tests/simplex/step-23.cc
index 2cf375d5de223aa4fe0f6acc9e654dd467d8fd90..1a8dee444d255d681624611db3df5f06fe503929 100644 (file)
--- a/tests/simplex/step-23.cc
+++ b/tests/simplex/step-23.cc
@@ -14,7 +14,12 @@
 // ---------------------------------------------------------------------
 
 
-// Step-23 with tetrahedron mesh.
+// Step-23 with tetrahedron mesh. Following incompatible modifications had to be
+// made:
+// - Change FE_Q and QGauss to Simplex::FE_P and Simplex::QGauss.
+// - Explicit use of MappingFE instead of the default mapping.
+// - Grid generation by subdivided_hyper_cube_with_simplices instead of
+// hyper_cube, because global refinement is not allowed.
 
 #include <deal.II/base/function.h>
 #include <deal.II/base/quadrature_lib.h>