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  • #include <config.h>
    
    #include <dune/common/bitsetvector.hh>
    #include <dune/common/configparser.hh>
    
    #include <dune/grid/uggrid.hh>
    #include <dune/grid/onedgrid.hh>
    
    #include <dune/grid/utility/structuredgridfactory.hh>
    
    #include <dune/grid/io/file/amirameshwriter.hh>
    
    
    #include <dune/ag-common/functionspacebases/p1nodalbasis.hh>
    #include <dune/ag-common/assemblers/operatorassembler.hh>
    #include <dune/ag-common/assemblers/localassemblers/laplaceassembler.hh>
    #include <dune/ag-common/assemblers/localassemblers/massassembler.hh>
    
    #include <dune/solvers/solvers/iterativesolver.hh>
    
    #include <dune/solvers/norms/h1seminorm.hh>
    
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    #include <dune/gfe/unitvector.hh>
    #include <dune/gfe/harmonicenergystiffness.hh>
    #include <dune/gfe/geodesicfeassembler.hh>
    #include <dune/gfe/riemanniantrsolver.hh>
    #include <dune/gfe/geodesicfefunctionadaptor.hh>
    
    
    // grid dimension
    const int dim = 2;
    
    typedef UnitVector<3> TargetSpace;
    typedef std::vector<TargetSpace> SolutionType;
    
    const int blocksize = TargetSpace::TangentVector::size;
    
    using namespace Dune;
    using std::string;
    
    template <class GridType>
    void solve (const shared_ptr<GridType>& grid,
                SolutionType& x, 
                int numLevels,
                ConfigParser& parameters)
    {
        // read solver setting
        const double innerTolerance           = parameters.get<double>("innerTolerance");
        const double tolerance                = parameters.get<double>("tolerance");
        const int maxTrustRegionSteps         = parameters.get<int>("maxTrustRegionSteps");
        const double initialTrustRegionRadius = parameters.get<double>("initialTrustRegionRadius");
        const int multigridIterations         = parameters.get<int>("numIt");
    
        // /////////////////////////////////////////
        //   Read Dirichlet values
        // /////////////////////////////////////////
    
        BitSetVector<1> allNodes(grid->size(dim));
        allNodes.setAll();
        LeafBoundaryPatch<GridType> dirichletBoundary(*grid, allNodes);
    
        BitSetVector<blocksize> dirichletNodes(grid->size(dim));
        for (int i=0; i<dirichletNodes.size(); i++)
            dirichletNodes[i] = dirichletBoundary.containsVertex(i);
    
        // //////////////////////////
        //   Initial solution
        // //////////////////////////
    
        x.resize(grid->size(dim));
    
            FieldVector<double,3> yAxis(0);
        yAxis[1] = 1;
    
        typename GridType::LeafGridView::template Codim<dim>::Iterator vIt    = grid->template leafbegin<dim>();
        typename GridType::LeafGridView::template Codim<dim>::Iterator vEndIt = grid->template leafend<dim>();
    
        for (; vIt!=vEndIt; ++vIt) {
            int idx = grid->leafIndexSet().index(*vIt);
    
            FieldVector<double,3> v;
            FieldVector<double,2> pos = vIt->geometry().corner(0);
            FieldVector<double,3> axis;
            axis[0] = pos[0];  axis[1] = pos[1]; axis[2] = 1;
    
            Rotation<3,double> rotation(axis, pos.two_norm()*M_PI*3);
    
    #if 1
                FieldMatrix<double,3,3> rMat;
                rotation.matrix(rMat);
                v = rMat[2];
    #else
    
                v[0] = std::sin(pos[0]*M_PI);
                v[1] = 0;
                v[2] = std::cos(pos[0]*M_PI);
    
    #endif
    
            } else {
                v[0] = 1;
                v[1] = 0;
                v[2] = 0;
            }            
    
            x[idx] = v;
    
        }
    
    
        // ////////////////////////////////////////////////////////////
        //   Create an assembler for the Harmonic Energy Functional
        // ////////////////////////////////////////////////////////////
    
        HarmonicEnergyLocalStiffness<typename GridType::LeafGridView,TargetSpace> harmonicEnergyLocalStiffness;
    
        GeodesicFEAssembler<typename GridType::LeafGridView,TargetSpace> assembler(grid->leafView(),
                                                                          &harmonicEnergyLocalStiffness);
        
        // ///////////////////////////////////////////
        //   Create a solver for the rod problem
        // ///////////////////////////////////////////
    
        RiemannianTrustRegionSolver<GridType,TargetSpace> solver;
    
        solver.setup(*grid, 
                     &assembler,
                     x,
                     dirichletNodes,
                     tolerance,
                     maxTrustRegionSteps,
                     initialTrustRegionRadius,
                     multigridIterations,
                     innerTolerance,
                     1, 3, 3,
                     100,     // iterations of the base solver
                     1e-8,    // base tolerance
                     false);  // instrumentation
    
        // /////////////////////////////////////////////////////
        //   Solve!
        // /////////////////////////////////////////////////////
    
        solver.setInitialSolution(x);
        solver.solve();
    
        x = solver.getSol();
    }
    
    int main (int argc, char *argv[]) try
    {
        // parse data file
        ConfigParser parameterSet;
        if (argc==2)
            parameterSet.parseFile(argv[1]);
        else
            parameterSet.parseFile("harmonicmaps-eoc.parset");
    
        // read solver settings
        const int numLevels        = parameterSet.get<int>("numLevels");
        const int baseIterations      = parameterSet.get<int>("baseIt");
        const double baseTolerance    = parameterSet.get<double>("baseTolerance");
    
        const int numBaseElements = parameterSet.get<int>("numBaseElements");
        
        // /////////////////////////////////////////
        //   Read Dirichlet values
        // /////////////////////////////////////////
    
        
    
    
        // ///////////////////////////////////////////////////////////
        //   First compute the 'exact' solution on a very fine grid
        // ///////////////////////////////////////////////////////////
    
        typedef std::conditional<dim==1,OneDGrid,UGGrid<dim> >::type GridType;
    
        //    Create the reference grid
    
        array<unsigned int,dim> elements;
    
        elements.fill(numBaseElements);
    
        shared_ptr<GridType> referenceGrid = StructuredGridFactory<GridType>::createSimplexGrid(FieldVector<double,dim>(0),
                                                                                                FieldVector<double,dim>(1),
                                                                                                elements);
        referenceGrid->globalRefine(numLevels-1);
    
        //  Solve the rod Dirichlet problem
        SolutionType referenceSolution;
        solve(referenceGrid, referenceSolution, numLevels, parameterSet);
    
        // //////////////////////////////////////////////////////////////////////
        //   Compute mass matrix and laplace matrix to emulate L2 and H1 norms
        // //////////////////////////////////////////////////////////////////////
    
        typedef P1NodalBasis<GridType::LeafGridView,double> FEBasis;
        FEBasis basis(referenceGrid->leafView());
        OperatorAssembler<FEBasis,FEBasis> operatorAssembler(basis, basis);
    
        LaplaceAssembler<GridType, FEBasis::LocalFiniteElement, FEBasis::LocalFiniteElement> laplaceLocalAssembler;
        MassAssembler<GridType, FEBasis::LocalFiniteElement, FEBasis::LocalFiniteElement> massMatrixLocalAssembler;
    
        typedef Dune::BCRSMatrix<Dune::FieldMatrix<double,1,1> > ScalarMatrixType;
        ScalarMatrixType laplace, massMatrix;
    
        operatorAssembler.assemble(laplaceLocalAssembler, laplace);
        operatorAssembler.assemble(massMatrixLocalAssembler, massMatrix);
    
        // ///////////////////////////////////////////////////////////
        //   Compute on all coarser levels, and compare
        // ///////////////////////////////////////////////////////////
        
        for (int i=1; i<=numLevels; i++) {
    
            array<unsigned int,dim> elements;
            elements.fill(numBaseElements);
            shared_ptr<GridType> grid = StructuredGridFactory<GridType>::createSimplexGrid(FieldVector<double,dim>(0),
                                                                                           FieldVector<double,dim>(1),
                                                                                           elements);
    
            grid->globalRefine(i-1);
    
            // compute again
            SolutionType solution;
            solve(grid, solution, i, parameterSet);
    
    
            // write solution
            std::stringstream numberAsAscii;
            numberAsAscii << i;
    
            BlockVector<FieldVector<double,3> > xEmbedded(solution.size());
            for (int j=0; j<solution.size(); j++)
                xEmbedded[j] = solution[j].globalCoordinates();
            
            LeafAmiraMeshWriter<GridType> amiramesh;
            amiramesh.addGrid(grid->leafView());
            amiramesh.addVertexData(xEmbedded, grid->leafView());
            amiramesh.write("harmonic_result_" + numberAsAscii.str() + ".am");
    
    
            // Prolong solution to the very finest grid
            for (int j=i; j<numLevels; j++)
    
                geodesicFEFunctionAdaptor(*grid, solution);
    
            //assert(referenceSolution.size() == solution.size());
    
    #if 0
    
            xEmbedded.resize(solution.size());
            for (int j=0; j<solution.size(); j++)
                xEmbedded[j] = solution[j].globalCoordinates();
    
            LeafAmiraMeshWriter<GridType> amirameshRefined;
            amirameshRefined.addGrid(grid->leafView());
            amirameshRefined.addVertexData(xEmbedded, grid->leafView());
            amirameshRefined.write("harmonic_result_" + numberAsAscii.str() + "_refined.am");
    
    #endif
    
            // Interpret TargetSpace as isometrically embedded into an R^m, because this is
            // how the corresponding Sobolev spaces are defined.
    
            BlockVector<TargetSpace::TangentVector> difference(referenceSolution.size());
    
            for (int j=0; j<referenceSolution.size(); j++)
                difference[j] = solution[j].globalCoordinates() - referenceSolution[j].globalCoordinates();
    
    
            H1SemiNorm< BlockVector<TargetSpace::TangentVector> > h1Norm(laplace);
            H1SemiNorm< BlockVector<TargetSpace::TangentVector> > l2Norm(massMatrix);
    
            // Compute max-norm difference
            std::cout << "Level: " << i-1 
                      << ",   max-norm error: " << difference.infinity_norm()
                      << std::endl;
    
            std::cout << "Level: " << i-1 
                      << ",   L2 error: " << l2Norm(difference)
                      << std::endl;
    
            std::cout << "Level: " << i-1 
                      << ",   H1 error: " << h1Norm(difference)
                      << std::endl;