u_diff_old -> u_diff_saved

_old denotes anything from the old timestep

src/one-body-sample.cc

@@ -273,7 +273,7 @@ int main(int argc, char *argv[]) {
           auto multigridStep = mySolver.getSolver();
           multigridStep->setProblem(u_diff, myBlockProblem);
 
-          VectorType const u_diff_old = u_diff;
+          VectorType const u_diff_saved = u_diff;
           LoopSolver<VectorType> overallSolver(
               multigridStep, parset.get<size_t>("solver.tnnmg.maxiterations"),
               solver_tolerance, &energyNorm, verbosity,
@@ -304,7 +304,7 @@ int main(int argc, char *argv[]) {
             std::cout << '.';
             std::cout.flush();
           }
-          if (energyNorm.diff(u_diff_old, u_diff) <
+          if (energyNorm.diff(u_diff_saved, u_diff) <
               parset.get<double>("solver.tnnmg.fixed_point_tolerance"))
             break;
         }