Add convenience method for absulute norm criterion

dune/solvers/solvers/criterion.hh

@@ -207,6 +207,54 @@ namespace Dune {
                 "   iter");
     }
 
+    /**
+     * \brief Create a Criterion for checking the correction norm
+     *
+     * \param iterationStep The IterationStep to be monitored
+     * \param norm          Norm to be evaluated for the correction
+     * \param tolerance     Tolerance necessary to satisfy the criterion
+     * \param correctionNorms A container to store the computed correction norms
+     */
+    template<class IterationStepType, class NormType, class CorrectionNormContainer>
+    Criterion correctionNormCriterion(
+          const IterationStepType& iterationStep,
+          const NormType& norm,
+          double tolerance,
+          CorrectionNormContainer& correctionNorms)
+    {
+      auto lastIterate = std::make_shared<typename IterationStepType::Vector>(*iterationStep.getIterate());
+      return Criterion(
+          [&, lastIterate, tolerance] () mutable {
+            double normOfCorrection = norm.diff(*lastIterate, *iterationStep.getIterate());
+            correctionNorms.push_back(normOfCorrection);
+            *lastIterate = *iterationStep.getIterate();
+            return std::make_tuple(normOfCorrection < tolerance, Dune::formatString(" % 14.7e", normOfCorrection));
+          },
+          " abs correction");
+    }
+
+    /**
+     * \brief Create a Criterion for checking the correction norm
+     *
+     * \param iterationStep The IterationStep to be monitored
+     * \param norm          Norm to be evaluated for the correction
+     * \param tolerance     Tolerance necessary to satisfy the criterion
+     */
+    template<class IterationStepType, class NormType>
+    Criterion correctionNormCriterion(
+          const IterationStepType& iterationStep,
+          const NormType& norm,
+          double tolerance)
+    {
+      auto lastIterate = std::make_shared<typename IterationStepType::Vector>(*iterationStep.getIterate());
+      return Criterion(
+          [&, lastIterate, tolerance] () mutable {
+            double normOfCorrection = norm.diff(*lastIterate, *iterationStep.getIterate());
+            *lastIterate = *iterationStep.getIterate();
+            return std::make_tuple(normOfCorrection < tolerance, Dune::formatString(" % 14.7e", normOfCorrection));
+          },
+          " abs correction");
+    }
 
   } // end namespace Solvers