added vector space axpy to FieldMatrix

[[Imported from SVN: r5467]]

common/fmatrix.hh

@@ -277,6 +277,14 @@ namespace Dune {
       return *this;
     }
 
+    //! vector space axpy operation (*this += k y)
+    FieldMatrix &axpy ( const K &k, const FieldMatrix &y )
+    {
+      for( size_type i = 0; i < n; ++i )
+        p[ i ].axpy( k, y[ i ] );
+      return *this;
+    }
+
     //===== linear maps
 
     //! y = A x
@@ -1033,6 +1041,13 @@ namespace Dune {
       return *this;
     }
 
+    //! vector space axpy operation (*this += a y)
+    FieldMatrix &axpy ( const K &k, const FieldMatrix &y )
+    {
+      a[ 0 ] += k * y.a[ 0 ];
+      return *this;
+    }
+
     //===== linear maps
 
     //! y = A x

common/test/fmatrixtest.cc

@@ -219,6 +219,8 @@ void test_matrix()
   std::cout << A << std::endl;
   // print vector
   std::cout << f << std::endl;
+
+  A.axpy( K( 1 ), A );
 }
 
 int main()