Merge branch 'feature/#5-rightmultiply' into 'master'

Fix FieldMatrix::rightmultiply()

This addresses an issue mentioned in #5 and additionally turns runtime checks into compile-time checks whenever possible.

See merge request !22
(cherry picked from commit 71e2e4b8)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

dune/common/fmatrix.hh

@@ -134,9 +134,14 @@ namespace Dune
       return C;
     }
 
+    using Base::rightmultiply;
+
     //! Multiplies M from the right to this matrix
-    FieldMatrix& rightmultiply (const FieldMatrix<K,cols,cols>& M)
+    template <int r, int c>
+    FieldMatrix& rightmultiply (const FieldMatrix<K,r,c>& M)
     {
+      static_assert(r == c, "Cannot rightmultiply with non-square matrix");
+      static_assert(r == cols, "Size mismatch");
       FieldMatrix<K,rows,cols> C(*this);
 
       for (size_type i=0; i<rows; i++)