Use Arithmetic::addProduct instead of StaticMatrix::axpy.

dune/solvers/transferoperators/compressedmultigridtransfer.hh

@@ -265,7 +265,7 @@ public:
                 size_t j = j_it.index();
 
                 for (size_t k=0; k<lr_fine_factor.N(); ++k)
-                    StaticMatrix::axpy(lr_coarse_factor[k][j], *j_it, lr_fine_factor[k][i]);
+                    Arithmetic::addProduct(lr_coarse_factor[k][j], *j_it, lr_fine_factor[k][i]);
             }
         }
     }