introduce method setRhs, in order to be able to solve a second problem with...

introduce method setRhs, in order to be able to solve a second problem with the same matrix without recomputing the grid hierarchy

[[Imported from SVN: r6543]]

dune/solvers/iterationsteps/multigridstep.hh

@@ -137,6 +137,11 @@
             preprocessCalled = false;
         }
 
+        void setRhs(const VectorType& rhs)
+        {
+            rhs_[numLevels_-1] = rhs;
+        }
+
         template <class DerivedTransferHierarchy>
         void setTransferOperators(const DerivedTransferHierarchy& transfer)
         {