remove Exception from Hdiv_seminorm

also add some comments

diff --git a/include/deal.II/numerics/vector_tools.templates.h b/include/deal.II/numerics/vector_tools.templates.h
index e5821a98d0f2662b33b6232fcea120765b16eeb1..8b6d4c272b82cf8ecb4985fc9ad5627aa76374f7 100644 (file)
--- a/include/deal.II/numerics/vector_tools.templates.h
+++ b/include/deal.II/numerics/vector_tools.templates.h
@@ -6218,6 +6218,8 @@ namespace VectorTools
         }
 
       double diff = 0;
+
+      // First work on function values:
       switch (norm)
         {
         case mean:
@@ -6245,7 +6247,7 @@ namespace VectorTools
               diff += sum * fe_values.JxW(q);
             }
 
-          // Compute the root only, if no derivative values are added later
+          // Compute the root only if no derivative values are added later
           if (!(update_flags & update_gradients))
             diff = std::pow(diff, 1./exponent);
           break;
@@ -6275,8 +6277,10 @@ namespace VectorTools
           break;
 
         case H1_seminorm:
+        case Hdiv_seminorm:
         case W1p_seminorm:
         case W1infty_seminorm:
+          // function values are not used for these norms
           break;
 
         default:
@@ -6284,6 +6288,7 @@ namespace VectorTools
           break;
         }
 
+      // Now compute terms depending on derivatives:
       switch (norm)
         {
         case W1p_seminorm: