Inject resize from SumOperator.

dune/solvers/operators/sumoperator.hh

@@ -4,6 +4,7 @@
 #define SUMOPERATOR_HH
 
 #include <cstddef>
+#include <dune/matrix-vector/resize.hh>
 
 /** \brief represents the sum of two linear operators
  *
@@ -139,5 +140,14 @@ class SumOperator
         const bool summands_allocated_internally_;
 };
 
+//! inject the resize from SumOperator to generic vector tools
+namespace Dune { namespace MatrixVector {
+template <class Vector, class SparseMatrix, class LowRankMatrix>
+//! Resize vector from SumOperator. Note that we only consider the sparse part.
+void resize(Vector& v, const SumOperator<SparseMatrix, LowRankMatrix>& sumOp) {
+  resize(v, sumOp.sparseMatrix());
+}
+}}
+
 #endif