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    25239378
    Replace RigidBodyMotion by ProductManifold · 25239378
    Sander, Oliver authored
    The ProductManifold class generalizes RigidBodyMotion, and can do
    everything that the RigidBodyMotion class can.  Therefore there is
    no point in keeping RigidBodyMotion any longer.  Having two
    implementations for the same thing will just confuse people.
    25239378
    History
    Replace RigidBodyMotion by ProductManifold
    Sander, Oliver authored
    The ProductManifold class generalizes RigidBodyMotion, and can do
    everything that the RigidBodyMotion class can.  Therefore there is
    no point in keeping RigidBodyMotion any longer.  Having two
    implementations for the same thing will just confuse people.
compute-disc-error.cc 38.90 KiB
#include <config.h>

#include <array>

#include <dune/common/parametertree.hh>
#include <dune/common/parametertreeparser.hh>

#include <dune/grid/uggrid.hh>
#include <dune/grid/common/mcmgmapper.hh>
#include <dune/grid/io/file/gmshreader.hh>
#include <dune/grid/utility/structuredgridfactory.hh>

#if HAVE_DUNE_FOAMGRID
#include <dune/foamgrid/foamgrid.hh>
#else
#include <dune/grid/onedgrid.hh>
#endif

#include <dune/functions/functionspacebases/lagrangebasis.hh>

#include <dune/matrix-vector/genericvectortools.hh>

#include <dune/fufem/discretizationerror.hh>
#include <dune/fufem/dunepython.hh>
#include <dune/fufem/makesphere.hh>

#include <dune/gfe/localgeodesicfefunction.hh>
#include <dune/gfe/localprojectedfefunction.hh>
#include <dune/gfe/embeddedglobalgfefunction.hh>
#include <dune/gfe/spaces/realtuple.hh>
#include <dune/gfe/spaces/rotation.hh>
#include <dune/gfe/spaces/unitvector.hh>

// grid dimension
const int dim = 2;
const int dimworld = 2;

using namespace Dune;

/** \brief Check whether given local coordinates are contained in the reference element
    \todo This method exists in the Dune grid interface!  But we need the eps.
 */
static bool checkInside(const Dune::GeometryType& type,
                        const Dune::FieldVector<double, dim> &loc,
                        double eps)
{
  switch (type.dim())
  {
  case 0 :  // vertex
    return false;

  case 1 :  // line
    return -eps <= loc[0] && loc[0] <= 1+eps;

  case 2 :

    if (type.isSimplex()) {
      return -eps <= loc[0] && -eps <= loc[1] && (loc[0]+loc[1])<=1+eps;
    } else if (type.isCube()) {
      return -eps <= loc[0] && loc[0] <= 1+eps
             && -eps <= loc[1] && loc[1] <= 1+eps;
    } else
      DUNE_THROW(Dune::GridError, "checkInside():  ERROR:  Unknown type " << type << " found!");

  case 3 :
    if (type.isSimplex()) {
      return -eps <= loc[0] && -eps <= loc[1] && -eps <= loc[2]
             && (loc[0]+loc[1]+loc[2]) <= 1+eps;
    } else if (type.isPyramid()) {
      return -eps <= loc[0] && -eps <= loc[1] && -eps <= loc[2]
             && (loc[0]+loc[2]) <= 1+eps
             && (loc[1]+loc[2]) <= 1+eps;
    } else if (type.isPrism()) {
      return -eps <= loc[0] && -eps <= loc[1]
             && (loc[0]+loc[1])<= 1+eps
             && -eps <= loc[2] && loc[2] <= 1+eps;
    } else if (type.isCube()) {
      return -eps <= loc[0] && loc[0] <= 1+eps
             && -eps <= loc[1] && loc[1] <= 1+eps
             && -eps <= loc[2] && loc[2] <= 1+eps;
    }else
      DUNE_THROW(Dune::GridError, "checkInside():  ERROR:  Unknown type " << type << " found!");

  default :
    DUNE_THROW(Dune::GridError, "checkInside():  ERROR:  Unknown type " << type << " found!");
  }

}

/** \param element An element of the source grid
 */
template <class GridType>
auto findSupportingElement(const GridType& sourceGrid,
                           const GridType& targetGrid,
                           typename GridType::template Codim<0>::Entity element,
                           FieldVector<double,dim> pos)
{
  while (element.level() != 0)
  {
    pos = element.geometryInFather().global(pos);
    element = element.father();

    assert(checkInside(element.type(), pos, 1e-7));
  }

  //////////////////////////////////////////////////////////////////////
  //   Find the corresponding coarse grid element on the adaptive grid.
  //   This is a linear algorithm, but we expect the coarse grid to be small.
  //////////////////////////////////////////////////////////////////////
  MultipleCodimMultipleGeomTypeMapper<typename GridType::LevelGridView> sourceP0Mapper (sourceGrid.levelGridView(0), mcmgElementLayout());
  MultipleCodimMultipleGeomTypeMapper<typename GridType::LevelGridView> targetP0Mapper(targetGrid.levelGridView(0), mcmgElementLayout());
  const auto coarseIndex = sourceP0Mapper.index(element);

  auto targetLevelView = targetGrid.levelGridView(0);

  for (auto&& targetElement : elements(targetLevelView))
    if (targetP0Mapper.index(targetElement) == coarseIndex)
    {
      element = std::move(targetElement);
      break;
    }

  //////////////////////////////////////////////////////////////////////////
  //   Find a corresponding point (not necessarily vertex) on the leaf level
  //   of the adaptive grid.
  //////////////////////////////////////////////////////////////////////////

  while (!element.isLeaf())
  {
    FieldVector<double,dim> childPos;
    assert(checkInside(element.type(), pos, 1e-7));

    auto hIt    = element.hbegin(element.level()+1);
    auto hEndIt = element.hend(element.level()+1);

    for (; hIt!=hEndIt; ++hIt)
    {
      childPos = hIt->geometryInFather().local(pos);
      if (checkInside(hIt->type(), childPos, 1e-7))
        break;
    }

    element = *hIt;
    pos     = childPos;
  }

  return std::make_tuple(element, pos);
}

template <class GridView, int order, class TargetSpace>
void measureDiscreteEOC(const GridView gridView,
                        const GridView referenceGridView,
                        const ParameterTree& parameterSet)
{
  typedef std::vector<TargetSpace> SolutionType;

  //////////////////////////////////////////////////////////////////////////////////
  //  Construct the scalar function space bases corresponding to the GFE space
  //////////////////////////////////////////////////////////////////////////////////

  typedef Dune::Functions::LagrangeBasis<GridView, order> FEBasis;
  FEBasis feBasis(gridView);
  FEBasis referenceFEBasis(referenceGridView);

  //typedef LocalGeodesicFEFunction<GridView::dimension, double, typename FEBasis::LocalView::Tree::FiniteElement, TargetSpace> LocalInterpolationRule;
  //if (parameterSet["interpolationMethod"] != "geodesic")
  //  DUNE_THROW(Exception, "Inconsistent choice of interpolation method");
  typedef GFE::LocalProjectedFEFunction<GridView::dimension, double, typename FEBasis::LocalView::Tree::FiniteElement, TargetSpace> LocalInterpolationRule;
  if (parameterSet["interpolationMethod"] != "projected")
    DUNE_THROW(Exception, "Inconsistent choice of interpolation method");
  std::cout << "Using local interpolation: " << className<LocalInterpolationRule>() << std::endl;

  //////////////////////////////////////////////////////////////////////////////////
  //  Read the data whose error is to be measured
  //////////////////////////////////////////////////////////////////////////////////

  // Input data
  typedef BlockVector<typename TargetSpace::CoordinateType> EmbeddedVectorType;

  EmbeddedVectorType embeddedX(feBasis.size());
  std::ifstream inFile(parameterSet.get<std::string>("simulationData"), std::ios_base::binary);
  if (not inFile)
    DUNE_THROW(IOError, "File " << parameterSet.get<std::string>("simulationData") << " could not be opened.");
  MatrixVector::Generic::readBinary(inFile, embeddedX);
  inFile.peek();   // try to advance beyond the end of the file
  if (not inFile.eof())
    DUNE_THROW(IOError, "File '" << parameterSet.get<std::string>("simulationData") << "' does not have the correct size!");
  inFile.close();

  SolutionType x(embeddedX.size());
  for (size_t i=0; i<x.size(); i++)
    x[i] = TargetSpace(embeddedX[i]);

  // The numerical solution, as a grid function
  GFE::EmbeddedGlobalGFEFunction<FEBasis, LocalInterpolationRule, TargetSpace> numericalSolution(feBasis, x);

  ///////////////////////////////////////////////////////////////////////////
  // Read the reference configuration
  ///////////////////////////////////////////////////////////////////////////
  EmbeddedVectorType embeddedReferenceX(referenceFEBasis.size());
  inFile.open(parameterSet.get<std::string>("referenceData"), std::ios_base::binary);
  if (not inFile)
    DUNE_THROW(IOError, "File " << parameterSet.get<std::string>("referenceData") << " could not be opened.");
  MatrixVector::Generic::readBinary(inFile, embeddedReferenceX);
  inFile.peek();   // try to advance beyond the end of the file
  if (not inFile.eof())
    DUNE_THROW(IOError, "File '" << parameterSet.get<std::string>("referenceData") << "' does not have the correct size!");

  SolutionType referenceX(embeddedReferenceX.size());
  for (size_t i=0; i<referenceX.size(); i++)
    referenceX[i] = TargetSpace(embeddedReferenceX[i]);

  // The reference solution, as a grid function
  GFE::EmbeddedGlobalGFEFunction<FEBasis, LocalInterpolationRule, TargetSpace> referenceSolution(referenceFEBasis, referenceX);

  /////////////////////////////////////////////////////////////////
  //   Measure the discretization error
  /////////////////////////////////////////////////////////////////

  HierarchicSearch<typename GridView::Grid,typename GridView::IndexSet> hierarchicSearch(gridView.grid(), gridView.indexSet());

  auto localReferenceSolution = localFunction(referenceSolution);
  auto localNumericalSolution = localFunction(numericalSolution);

  if (std::is_same<TargetSpace,GFE::ProductManifold<RealTuple<double,3>,Rotation<double,3> > >::value)
  {
    double deformationL2ErrorSquared = 0;
    double orientationL2ErrorSquared = 0;
    double deformationH1ErrorSquared = 0;
    double orientationH1ErrorSquared = 0;

    for (const auto& rElement : elements(referenceGridView))
    {
      localReferenceSolution.bind(rElement);
      auto localReferenceDerivative = derivative(localReferenceSolution);

      const auto& quadRule = QuadratureRules<double, dim>::rule(rElement.type(), 6);

      for (const auto& qp : quadRule)
      {
        auto integrationElement = rElement.geometry().integrationElement(qp.position());

        auto globalPos = rElement.geometry().global(qp.position());

        auto element = hierarchicSearch.findEntity(globalPos);
        localNumericalSolution.bind(element);
        auto localNumericalDerivative = derivative(localNumericalSolution);
        auto localPos = element.geometry().local(globalPos);

        auto refValue = localReferenceSolution(qp.position());
        auto numValue = localNumericalSolution(localPos);
        auto diff = refValue - numValue;
        assert(diff.size()==7);

        // Compute error of the displacement degrees of freedom
        for (int i=0; i<3; i++)
          deformationL2ErrorSquared += integrationElement * qp.weight() * diff[i] * diff[i];

        auto derDiff = localReferenceDerivative(qp.position()) - localNumericalDerivative(localPos);

        for (int i=0; i<3; i++)
          deformationH1ErrorSquared += integrationElement * qp.weight() * derDiff[i].two_norm2();

        // Compute error of the orientation degrees of freedom
        // We need to transform from quaternion coordinates to matrix coordinates first.
        FieldMatrix<double,3,3> referenceValue, numericalValue;
        Rotation<double,3> referenceRotation(std::array<double,4>{refValue[3], refValue[4], refValue[5], refValue[6]});
        referenceRotation.matrix(referenceValue);

        Rotation<double,3> numericalRotation(std::array<double,4>{numValue[3], numValue[4], numValue[5], numValue[6]});
        numericalRotation.matrix(numericalValue);

        auto orientationDiff = referenceValue - numericalValue;

        orientationL2ErrorSquared += integrationElement * qp.weight() * orientationDiff.frobenius_norm2();

        auto referenceDerQuat = localReferenceDerivative(qp.position());
        auto numericalDerQuat = localNumericalDerivative(localPos);

        // Transform to matrix coordinates
        Tensor3<double,3,3,4> derivativeQuaternionToMatrixRef = Rotation<double,3>::derivativeOfQuaternionToMatrix(FieldVector<double,4>{refValue[3], refValue[4], refValue[5], refValue[6]});
        Tensor3<double,3,3,4> derivativeQuaternionToMatrixNum = Rotation<double,3>::derivativeOfQuaternionToMatrix(FieldVector<double,4>{numValue[3], numValue[4], numValue[5], numValue[6]});

        Tensor3<double,3,3,dim> refDerivative(0);
        Tensor3<double,3,3,dim> numDerivative(0);

        for (int i=0; i<3; i++)
          for (int j=0; j<3; j++)
            for (int k=0; k<dim; k++)
              for (int l=0; l<4; l++)
              {
                refDerivative[i][j][k] += derivativeQuaternionToMatrixRef[i][j][l] * referenceDerQuat[3+l][k];
                numDerivative[i][j][k] += derivativeQuaternionToMatrixNum[i][j][l] * numericalDerQuat[3+l][k];
              }

        auto derOrientationDiff = refDerivative - numDerivative;  // compute the difference
        orientationH1ErrorSquared += derOrientationDiff.frobenius_norm2() * qp.weight() * integrationElement;
      }
    }

    std::cout << "levels: " << gridView.grid().maxLevel()+1
              << "      "
              << "L^2 error deformation: " << std::sqrt(deformationL2ErrorSquared)
              << "      "
              << "L^2 error orientation: " << std::sqrt(orientationL2ErrorSquared)
              << "      "
              << "H^1 error deformation: " << std::sqrt(deformationH1ErrorSquared)
              << "      "
              << "H^1 error orientation: " << std::sqrt(orientationH1ErrorSquared)
              << std::endl;
  }
  else if constexpr (std::is_same<TargetSpace,Rotation<double,3> >::value)
  {
    double l2ErrorSquared = 0;
    double h1ErrorSquared = 0;

    for (const auto& rElement : elements(referenceGridView))
    {
      localReferenceSolution.bind(rElement);
      auto localReferenceDerivative = derivative(localReferenceSolution);

      const auto& quadRule = QuadratureRules<double, dim>::rule(rElement.type(), 6);

      for (const auto& qp : quadRule)
      {
        auto integrationElement = rElement.geometry().integrationElement(qp.position());

        auto globalPos = rElement.geometry().global(qp.position());

        auto element = hierarchicSearch.findEntity(globalPos);
        localNumericalSolution.bind(element);
        auto localNumericalDerivative = derivative(localNumericalSolution);
        auto localPos = element.geometry().local(globalPos);

        FieldMatrix<double,3,3> referenceValue, numericalValue;
        auto refValue = localReferenceSolution(qp.position());
        Rotation<double,3> referenceRotation(refValue);
        referenceRotation.matrix(referenceValue);

        auto numValue = localNumericalSolution(localPos);
        Rotation<double,3> numericalRotation(numValue);
        numericalRotation.matrix(numericalValue);

        auto diff = referenceValue - numericalValue;

        l2ErrorSquared += integrationElement * qp.weight() * diff.frobenius_norm2();

        auto referenceDerQuat = localReferenceDerivative(qp.position());
        auto numericalDerQuat = localNumericalDerivative(localPos);
        // Transform to matrix coordinates
        Tensor3<double,3,3,4> derivativeQuaternionToMatrixRef = Rotation<double,3>::derivativeOfQuaternionToMatrix(refValue);
        Tensor3<double,3,3,4> derivativeQuaternionToMatrixNum = Rotation<double,3>::derivativeOfQuaternionToMatrix(numValue);

        Tensor3<double,3,3,dim> refDerivative(0);
        Tensor3<double,3,3,dim> numDerivative(0);

        for (int i=0; i<3; i++)
          for (int j=0; j<3; j++)
            for (int k=0; k<dim; k++)
              for (int l=0; l<4; l++)
              {
                refDerivative[i][j][k] += derivativeQuaternionToMatrixRef[i][j][l] * referenceDerQuat[l][k];
                numDerivative[i][j][k] += derivativeQuaternionToMatrixNum[i][j][l] * numericalDerQuat[l][k];
              }

        auto derDiff = refDerivative - numDerivative;  // compute the difference
        h1ErrorSquared += derDiff.frobenius_norm2() * qp.weight() * integrationElement;

      }
    }

    std::cout << "levels: " << gridView.grid().maxLevel()+1
              << "      "
              << "L^2 error: " << std::sqrt(l2ErrorSquared)
              << "      "
              << "h^1 error: " << std::sqrt(h1ErrorSquared)
              << std::endl;
  }
  else
  {
    double l2ErrorSquared = 0;
    double h1ErrorSquared = 0;

    for (const auto& rElement : elements(referenceGridView))
    {
      localReferenceSolution.bind(rElement);
      auto localReferenceDerivative = derivative(localReferenceSolution);

      const auto& quadRule = QuadratureRules<double, dim>::rule(rElement.type(), 6);

      for (const auto& qp : quadRule)
      {
        auto integrationElement = rElement.geometry().integrationElement(qp.position());

        // Given a point with local coordinates qp.position() on element rElement of the reference grid
        // find the element and local coordinates on the grid of the numerical simulation
        auto supportingElement = findSupportingElement(referenceGridView.grid(),
                                                       gridView.grid(),
                                                       rElement, qp.position());
        auto element  = std::get<0>(supportingElement);
        localNumericalSolution.bind(element);
        auto localNumericalDerivative = derivative(localNumericalSolution);
        auto localPos = std::get<1>(supportingElement);

        auto diff = localReferenceSolution(qp.position()) - localNumericalSolution(localPos);

        l2ErrorSquared += integrationElement * qp.weight() * diff.two_norm2();

        auto derDiff = localReferenceDerivative(qp.position()) - localNumericalDerivative(localPos);

        h1ErrorSquared += integrationElement * qp.weight() * derDiff.frobenius_norm2();

      }
    }

    std::cout << "levels: " << gridView.grid().maxLevel()+1
              << "      "
              << "L^2 error: " << std::sqrt(l2ErrorSquared)
              << "      "
              << "h^1 error: " << std::sqrt(h1ErrorSquared)
              << std::endl;
  }
}

template <class GridView, int order, class TargetSpace>
void measureAnalyticalEOC(const GridView gridView,
                          const ParameterTree& parameterSet)
{
  typedef std::vector<TargetSpace> SolutionType;

  //////////////////////////////////////////////////////////////////////////////////
  //  Construct the scalar function space bases corresponding to the GFE space
  //////////////////////////////////////////////////////////////////////////////////

  typedef Dune::Functions::LagrangeBasis<GridView, order> FEBasis;
  FEBasis feBasis(gridView);

  //////////////////////////////////////////////////////////////////////////////////
  //  Read the data whose error is to be measured
  //////////////////////////////////////////////////////////////////////////////////

  // Input data
  typedef BlockVector<typename TargetSpace::CoordinateType> EmbeddedVectorType;

  EmbeddedVectorType embeddedX(feBasis.size());
  std::ifstream inFile(parameterSet.get<std::string>("simulationData"), std::ios_base::binary);
  if (not inFile)
    DUNE_THROW(IOError, "File " << parameterSet.get<std::string>("simulationData") << " could not be opened.");
  MatrixVector::Generic::readBinary(inFile, embeddedX);
  inFile.peek();   // try to advance beyond the end of the file
  if (not inFile.eof())
    DUNE_THROW(IOError, "File '" << parameterSet.get<std::string>("simulationData") << "' does not have the correct size!");
  inFile.close();

  SolutionType x(embeddedX.size());
  for (size_t i=0; i<x.size(); i++)
    x[i] = TargetSpace(embeddedX[i]);

  /////////////////////////////////////////////////////////////////
  //   Measure the discretization error
  /////////////////////////////////////////////////////////////////

  // Read reference solution and its derivative into a Python function
#if DUNE_VERSION_GT(DUNE_FUFEM, 2, 9)
  Python::Module module = Python::import(parameterSet.get<std::string>("referenceSolution"));

  using Domain = FieldVector<double, dimworld>;
  using Range = typename TargetSpace::CoordinateType;
  auto referenceSolution = Python::makeDifferentiableFunction<Range(Domain)>(module.get("fdf"));
  auto referenceDerivative = derivative(referenceSolution);

  // TODO: We need to use a type-erasure wrapper here
  // Only used if // parameterSet["interpolationMethod"] == "geodesic"
  auto numericalSolutionGeodesic = GFE::EmbeddedGlobalGFEFunction<FEBasis,
      LocalGeodesicFEFunction<dim, double, typename FEBasis::LocalView::Tree::FiniteElement, TargetSpace>,
      TargetSpace> (feBasis, x);
  auto localNumericalSolutionGeodesic = localFunction(numericalSolutionGeodesic);

  // ONly used if parameterSet["interpolationMethod"] == "projected"
  auto numericalSolutionProjected = GFE::EmbeddedGlobalGFEFunction<FEBasis,
      GFE::LocalProjectedFEFunction<dim, double, typename FEBasis::LocalView::Tree::FiniteElement, TargetSpace>,
      TargetSpace> (feBasis, x);
  auto localNumericalSolutionProjected = localFunction(numericalSolutionProjected);
#else
  typedef VirtualDifferentiableFunction<FieldVector<double, dimworld>, typename TargetSpace::CoordinateType> FBase;

  Python::Module module = Python::import(parameterSet.get<std::string>("referenceSolution"));
  auto referenceSolution = module.get("fdf").toC<std::shared_ptr<FBase> >();
  // The numerical solution, as a grid function
  std::unique_ptr<VirtualGridViewFunction<GridView, typename TargetSpace::CoordinateType> > numericalSolution;

  if (parameterSet["interpolationMethod"] == "geodesic")
    numericalSolution = std::make_unique<GFE::EmbeddedGlobalGFEFunction<FEBasis,
        LocalGeodesicFEFunction<dim, double, typename FEBasis::LocalView::Tree::FiniteElement, TargetSpace>,
        TargetSpace> > (feBasis, x);

  if (parameterSet["interpolationMethod"] == "projected")
    numericalSolution = std::make_unique<GFE::EmbeddedGlobalGFEFunction<FEBasis,
        GFE::LocalProjectedFEFunction<dim, double, typename FEBasis::LocalView::Tree::FiniteElement, TargetSpace>,
        TargetSpace> > (feBasis, x);
#endif

  // QuadratureRule for the integral of the L^2 error
  QuadratureRuleKey quadKey(dim,6);

  // Compute errors in the L2 norm and the h1 seminorm.
  // SO(3)-valued maps need special treatment, because they are stored as quaternions,
  // but the errors need to be computed in matrix space.
  if constexpr (std::is_same<TargetSpace,Rotation<double,3> >::value)
  {
    constexpr int blocksize = TargetSpace::CoordinateType::dimension;

    // The error to be computed
    double l2ErrorSquared = 0;
    double h1ErrorSquared = 0;

    for (auto&& element : elements(gridView))
    {
#if DUNE_VERSION_GT(DUNE_FUFEM, 2, 9)
      localNumericalSolutionGeodesic.bind(element);
      localNumericalSolutionProjected.bind(element);
      auto localNumericalDerivativeGeodesic = derivative(localNumericalSolutionGeodesic);
      auto localNumericalDerivativeProjected = derivative(localNumericalSolutionProjected);
#endif

      // Get quadrature formula
      quadKey.setGeometryType(element.type());
      const auto& quad = QuadratureRuleCache<double, dim>::rule(quadKey);

      for (auto quadPoint : quad)
      {
        auto quadPos = quadPoint.position();
        const auto integrationElement = element.geometry().integrationElement(quadPos);
        const auto weight = quadPoint.weight();

        // Evaluate function a
#if DUNE_VERSION_GT(DUNE_FUFEM, 2, 9)
        FieldVector<double,blocksize> numValue;
        if (parameterSet["interpolationMethod"] == "geodesic")
          numValue = localNumericalSolutionGeodesic(quadPos);
        if (parameterSet["interpolationMethod"] == "projected")
          numValue = localNumericalSolutionProjected(quadPos);

        auto refValue = referenceSolution(element.geometry().global(quadPos));
#else
        FieldVector<double,blocksize> numValue;
        numericalSolution.get()->evaluateLocal(element, quadPos,numValue);

        // Evaluate function b.  If it is a grid function use that to speed up the evaluation
        FieldVector<double,blocksize> refValue;
        if (std::dynamic_pointer_cast<const VirtualGridViewFunction<GridView,FieldVector<double,blocksize> > >(referenceSolution))
          std::dynamic_pointer_cast<const VirtualGridViewFunction<GridView,FieldVector<double,blocksize> > >(referenceSolution)->evaluateLocal(element,
                                                                                                                                               quadPos,
                                                                                                                                               refValue
                                                                                                                                               );
        else
          referenceSolution->evaluate(element.geometry().global(quadPos), refValue);
#endif

        // Get error in matrix space
        Rotation<double,3> numRotation(numValue);
        FieldMatrix<double,3,3> numValueMatrix;
        numRotation.matrix(numValueMatrix);

        Rotation<double,3> refRotation(refValue);
        FieldMatrix<double,3,3> refValueMatrix;
        refRotation.matrix(refValueMatrix);

#if DUNE_VERSION_GT(DUNE_FUFEM, 2, 9)
        // Evaluate derivatives in quaternion space
        FieldMatrix<double,blocksize,dimworld> num_di;

        if (parameterSet["interpolationMethod"] == "geodesic")
          num_di = localNumericalDerivativeGeodesic(quadPos);
        if (parameterSet["interpolationMethod"] == "projected")
          num_di = localNumericalDerivativeProjected(quadPos);

        auto ref_di = referenceDerivative(element.geometry().global(quadPos));
#else
        // Evaluate derivatives in quaternion space
        FieldMatrix<double,blocksize,dimworld> num_di;
        FieldMatrix<double,blocksize,dimworld> ref_di;

        if (dynamic_cast<const VirtualGridViewFunction<GridView,FieldVector<double,blocksize> >*>(numericalSolution.get()))
          dynamic_cast<const VirtualGridViewFunction<GridView,FieldVector<double,blocksize> >*>(numericalSolution.get())->evaluateDerivativeLocal(element,
                                                                                                                                                  quadPos,
                                                                                                                                                  num_di);
        else
          numericalSolution->evaluateDerivative(element.geometry().global(quadPos), num_di);

        if (std::dynamic_pointer_cast<const VirtualGridViewFunction<GridView,FieldVector<double,blocksize> > >(referenceSolution))
          std::dynamic_pointer_cast<const VirtualGridViewFunction<GridView,FieldVector<double,blocksize> > >(referenceSolution)->evaluateDerivativeLocal(element,
                                                                                                                                                         quadPos,
                                                                                                                                                         ref_di);
        else
          referenceSolution->evaluateDerivative(element.geometry().global(quadPos), ref_di);
#endif

        // Transform into matrix space
        Tensor3<double,3,3,4> derivativeQuaternionToMatrixNum = Rotation<double,3>::derivativeOfQuaternionToMatrix(numValue);
        Tensor3<double,3,3,4> derivativeQuaternionToMatrixRef = Rotation<double,3>::derivativeOfQuaternionToMatrix(refValue);

        Tensor3<double,3,3,dim> numDerivative(0);
        Tensor3<double,3,3,dim> refDerivative(0);

        for (int i=0; i<3; i++)
          for (int j=0; j<3; j++)
            for (int k=0; k<dim; k++)
              for (int l=0; l<blocksize; l++)
              {
                numDerivative[i][j][k] += derivativeQuaternionToMatrixNum[i][j][l] * num_di[l][k];
                refDerivative[i][j][k] += derivativeQuaternionToMatrixRef[i][j][l] * ref_di[l][k];
              }

        // integrate error
        l2ErrorSquared += (numValueMatrix - refValueMatrix).frobenius_norm2() * weight * integrationElement;
        auto diff = numDerivative - refDerivative;
        h1ErrorSquared += diff.frobenius_norm2() * weight * integrationElement;
      }
    }

    std::cout << "elements: " << gridView.size(0)
              << "      "
              << "L^2 error: " << std::sqrt(l2ErrorSquared)
              << "      ";
    std::cout << "h^1 error: " << std::sqrt(h1ErrorSquared) << std::endl;
  }
  else
  {
#if DUNE_VERSION_GT(DUNE_FUFEM, 2, 9)
    double l2Error = -1;
    double h1Error = -1;

    if (parameterSet["interpolationMethod"] == "geodesic")
    {
      l2Error = Fufem::DiscretizationError::computeL2DifferenceSquared(numericalSolutionGeodesic,
                                                                       referenceSolution,
                                                                       quadKey);

      h1Error = Fufem::DiscretizationError::computeL2DifferenceSquared(derivative(numericalSolutionGeodesic),
                                                                       derivative(referenceSolution),
                                                                       quadKey);
    }

    if (parameterSet["interpolationMethod"] == "projected")
    {
      l2Error = Fufem::DiscretizationError::computeL2DifferenceSquared(numericalSolutionProjected,
                                                                       referenceSolution,
                                                                       quadKey);

      h1Error = Fufem::DiscretizationError::computeL2DifferenceSquared(derivative(numericalSolutionProjected),
                                                                       derivative(referenceSolution),
                                                                       quadKey);
    }

    std::cout << "elements: " << gridView.size(0)
              << "      "
              << "L^2 error: " << std::sqrt(l2Error)
#else
    auto l2Error = DiscretizationError<GridView>::computeL2Error(numericalSolution.get(),
                                                                 referenceSolution.get(),
                                                                 quadKey);

    auto h1Error = DiscretizationError<GridView>::computeH1HalfNormDifferenceSquared(gridView,
                                                                                     numericalSolution.get(),
                                                                                     referenceSolution.get(),
                                                                                     quadKey);

    std::cout << "elements: " << gridView.size(0)
              << "      "
              << "L^2 error: " << l2Error
#endif
      << "      ";
    std::cout << "h^1 error: " << std::sqrt(h1Error) << std::endl;
  }
}

template <class GridType, class TargetSpace>
void measureEOC(const std::shared_ptr<GridType> grid,
                const std::shared_ptr<GridType> referenceGrid,
                const ParameterTree& parameterSet)
{
  const int order = parameterSet.get<int>("order");

  if (parameterSet.get<std::string>("discretizationErrorMode")=="discrete")
  {
    referenceGrid->globalRefine(parameterSet.get<int>("numReferenceLevels")-1);

    switch (order)
    {
    case 1 :
      measureDiscreteEOC<typename GridType::LeafGridView,1,TargetSpace>(grid->leafGridView(), referenceGrid->leafGridView(), parameterSet);
      break;

    case 2 :
      measureDiscreteEOC<typename GridType::LeafGridView,2,TargetSpace>(grid->leafGridView(), referenceGrid->leafGridView(), parameterSet);
      break;
    case 3 :
      measureDiscreteEOC<typename GridType::LeafGridView,3,TargetSpace>(grid->leafGridView(), referenceGrid->leafGridView(), parameterSet);
      break;

    default :
      DUNE_THROW(NotImplemented, "Order '" << order << "' is not implemented");
    }
    return;  // Success
  }

  if (parameterSet.get<std::string>("discretizationErrorMode")=="analytical")
  {
    switch (order)
    {
    case 1 :
      measureAnalyticalEOC<typename GridType::LeafGridView,1,TargetSpace>(grid->leafGridView(), parameterSet);
      break;

    case 2 :
      measureAnalyticalEOC<typename GridType::LeafGridView,2,TargetSpace>(grid->leafGridView(), parameterSet);
      break;

    case 3 :
      measureAnalyticalEOC<typename GridType::LeafGridView,3,TargetSpace>(grid->leafGridView(), parameterSet);
      break;

    default :
      DUNE_THROW(NotImplemented, "Order '" << order << "' is not implemented");
    }
    return;  // Success
  }

  DUNE_THROW(NotImplemented, "Unknown discretization error mode encountered!");
}

int main (int argc, char *argv[]) try
{
  MPIHelper::instance(argc, argv);

  // Start Python interpreter
  Python::start();
  Python::Reference main = Python::import("__main__");
  Python::run("import math");

  Python::runStream()
    << std::endl << "import sys"
    << std::endl << "sys.path.append('/home/sander/dune/dune-gfe/problems')"
    << std::endl;

  // parse data file
  ParameterTree parameterSet;
  if (argc < 2)
    DUNE_THROW(Exception, "Usage: ./compute-disc-error <parameter file>");

  ParameterTreeParser::readINITree(argv[1], parameterSet);

  ParameterTreeParser::readOptions(argc, argv, parameterSet);

  // Print all parameters, to have them in the log file
  parameterSet.report();

  /////////////////////////////////////////
  //    Create the grids
  /////////////////////////////////////////
#if HAVE_DUNE_FOAMGRID
  typedef std::conditional<dim==1 or dim!=dimworld,FoamGrid<dim,dimworld>,UGGrid<dim> >::type GridType;
#else
  static_assert(dim==dimworld, "You need to have dune-foamgrid installed for dim != dimworld!");
  typedef std::conditional<dim==1,OneDGrid,UGGrid<dim> >::type GridType;
#endif

  const int numLevels = parameterSet.get<int>("numLevels");

  std::shared_ptr<GridType> grid, referenceGrid;

  FieldVector<double,dimworld> lower(0), upper(1);

  std::string structuredGridType = parameterSet["structuredGrid"];
  if (structuredGridType == "sphere")
  {
    if constexpr (dimworld==3)
    {
      grid          = makeSphereOnOctahedron<GridType>({0,0,0},1);
      referenceGrid = makeSphereOnOctahedron<GridType>({0,0,0},1);
    } else
      DUNE_THROW(Exception, "Dimworld must be 3 to create a sphere grid!");
  }
  else if (structuredGridType == "simplex" || structuredGridType == "cube")
  {
    lower = parameterSet.get<FieldVector<double,dimworld> >("lower");
    upper = parameterSet.get<FieldVector<double,dimworld> >("upper");

    auto elements = parameterSet.get<std::array<unsigned int,dim> >("elements");
    if (structuredGridType == "simplex")
    {
      grid          = StructuredGridFactory<GridType>::createSimplexGrid(lower, upper, elements);
      referenceGrid = StructuredGridFactory<GridType>::createSimplexGrid(lower, upper, elements);
    } else if (structuredGridType == "cube")
    {
      grid          = StructuredGridFactory<GridType>::createCubeGrid(lower, upper, elements);
      referenceGrid = StructuredGridFactory<GridType>::createCubeGrid(lower, upper, elements);
    } else
      DUNE_THROW(Exception, "Unknown structured grid type '" << structuredGridType << "' found!");
  }
  else
  {
    std::string path                = parameterSet.get<std::string>("path");
    std::string gridFile            = parameterSet.get<std::string>("gridFile");
    grid          = std::shared_ptr<GridType>(GmshReader<GridType>::read(path + "/" + gridFile));
    referenceGrid = std::shared_ptr<GridType>(GmshReader<GridType>::read(path + "/" + gridFile));
  }

  grid->globalRefine(numLevels-1);

  // Do the actual measurement
  const int targetDim = parameterSet.get<int>("targetDim");
  const std::string targetSpace = parameterSet.get<std::string>("targetSpace");

  switch (targetDim)
  {
  case 1 :
    if (targetSpace=="RealTuple")
    {
      measureEOC<GridType,RealTuple<double,1> >(grid,
                                                referenceGrid,
                                                parameterSet);
    } else if (targetSpace=="UnitVector")
    {
      measureEOC<GridType,UnitVector<double,1> >(grid,
                                                 referenceGrid,
                                                 parameterSet);
    } else
      DUNE_THROW(NotImplemented, "Target space '" << targetSpace << "' is not implemented");
    break;

  case 2 :
    if (targetSpace=="RealTuple")
    {
      measureEOC<GridType,RealTuple<double,2> >(grid,
                                                referenceGrid,
                                                parameterSet);
    } else if (targetSpace=="UnitVector")
    {
      measureEOC<GridType,UnitVector<double,2> >(grid,
                                                 referenceGrid,
                                                 parameterSet);
#if 0
    } else if (targetSpace=="Rotation")
    {
      measureEOC<GridType,Rotation<double,2> >(grid,
                                               referenceGrid,
                                               parameterSet);
    } else if (targetSpace=="RigidBodyMotion")
    {
      measureEOC<GridType,GFE::ProductManifold<RealTuple<double,2>,Rotation<double,2> > >(grid,
                                                                                          referenceGrid,
                                                                                          parameterSet);
#endif
    } else
      DUNE_THROW(NotImplemented, "Target space '" << targetSpace << "' is not implemented");
    break;

  case 3 :
    if (targetSpace=="RealTuple")
    {
      measureEOC<GridType,RealTuple<double,3> >(grid,
                                                referenceGrid,
                                                parameterSet);
    } else if (targetSpace=="UnitVector")
    {
      measureEOC<GridType,UnitVector<double,3> >(grid,
                                                 referenceGrid,
                                                 parameterSet);
    } else if (targetSpace=="Rotation")
    {
      measureEOC<GridType,Rotation<double,3> >(grid,
                                               referenceGrid,
                                               parameterSet);
    } else if (targetSpace=="RigidBodyMotion")
    {
      measureEOC<GridType,GFE::ProductManifold<RealTuple<double,3>,Rotation<double,3> > >(grid,
                                                                                          referenceGrid,
                                                                                          parameterSet);
    } else
      DUNE_THROW(NotImplemented, "Target space '" << targetSpace << "' is not implemented");
    break;

  case 4 :
    if (targetSpace=="RealTuple")
    {
      measureEOC<GridType,RealTuple<double,4> >(grid,
                                                referenceGrid,
                                                parameterSet);
    } else if (targetSpace=="UnitVector")
    {
      measureEOC<GridType,UnitVector<double,4> >(grid,
                                                 referenceGrid,
                                                 parameterSet);
#if 0
    } else if (targetSpace=="Rotation")
    {
      measureEOC<GridType,Rotation<double,4> >(grid,
                                               referenceGrid,
                                               parameterSet);
    } else if (targetSpace=="RigidBodyMotion")
    {
      measureEOC<GridType,GFE::ProductManifold<RealTuple<double,4>,Rotation<double,4> > >(grid,
                                                                                          referenceGrid,
                                                                                          parameterSet);
#endif
    } else
      DUNE_THROW(NotImplemented, "Target space '" << targetSpace << "' is not implemented");
    break;

  default :
    DUNE_THROW(NotImplemented, "Target dimension '" << targetDim << "' is not implemented");
  }

  return 0;
}
catch (Exception& e)
{
  std::cout << e << std::endl;
  return 1;
}