Add norm criterion to test

dune/tnnmg/test/gradientmethodtest.cc

@@ -184,10 +184,15 @@ void solveProblem(const MatrixType& mat, VectorType& x, const VectorType& rhs, c
             [&](){return Dune::formatString("   % 12.5e", stepRule.x_);},
             "   step size   ");
 
-
     solver.addCriterion(Dune::Solvers::maxIterCriterion(solver, maxIterations) | gradientCriterion);
 
+    std::vector<double> correctionNorms;
+    solver.addCriterion(Dune::Solvers::correctionNormCriterion(gradientStep, norm, 1e-4, correctionNorms));
+
+    solver.addCriterion(Dune::Solvers::correctionNormCriterion(gradientStep, norm, 1e-4));
+
     solver.solve();
+    std::cout << correctionNorms.size() << std::endl;
 }