Intrepid2_LegendreBasis_HVOL_TRI.hpp

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// @HEADER
// *****************************************************************************
//                           Intrepid2 Package
//
// Copyright 2007 NTESS and the Intrepid2 contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef Intrepid2_LegendreBasis_HVOL_TRI_h
#define Intrepid2_LegendreBasis_HVOL_TRI_h

#include <Kokkos_DynRankView.hpp>

#include <Intrepid2_config.h>

#include "Intrepid2_Basis.hpp"
#include "Intrepid2_IntegratedLegendreBasis_HGRAD_LINE.hpp"
#include "Intrepid2_Polynomials.hpp"
#include "Intrepid2_Utils.hpp"

namespace Intrepid2
{
  template<class DeviceType, class OutputScalar, class PointScalar,
           class OutputFieldType, class InputPointsType>
  struct Hierarchical_HVOL_TRI_Functor
  {
    using ExecutionSpace     = typename DeviceType::execution_space;
    using ScratchSpace       = typename ExecutionSpace::scratch_memory_space;
    using OutputScratchView  = Kokkos::View<OutputScalar*,ScratchSpace,Kokkos::MemoryTraits<Kokkos::Unmanaged>>;
    using PointScratchView   = Kokkos::View<PointScalar*, ScratchSpace,Kokkos::MemoryTraits<Kokkos::Unmanaged>>;
    
    using TeamPolicy = Kokkos::TeamPolicy<ExecutionSpace>;
    using TeamMember = typename TeamPolicy::member_type;
    
    EOperator opType_;
    
    OutputFieldType  output_;      // F,P
    InputPointsType  inputPoints_; // P,D
    
    int polyOrder_;
    int numFields_, numPoints_;
    
    size_t fad_size_output_;
    
    Hierarchical_HVOL_TRI_Functor(EOperator opType, OutputFieldType output, InputPointsType inputPoints, int polyOrder)
    : opType_(opType), output_(output), inputPoints_(inputPoints),
      polyOrder_(polyOrder),
      fad_size_output_(getScalarDimensionForView(output))
    {
      numFields_ = output.extent_int(0);
      numPoints_ = output.extent_int(1);
      INTREPID2_TEST_FOR_EXCEPTION(numPoints_ != inputPoints.extent_int(0), std::invalid_argument, "point counts need to match!");
      INTREPID2_TEST_FOR_EXCEPTION(numFields_ != (polyOrder_+1)*(polyOrder_+2)/2, std::invalid_argument, "output field size does not match basis cardinality");
    }
    
    KOKKOS_INLINE_FUNCTION
    void operator()( const TeamMember & teamMember ) const
    {
      auto pointOrdinal = teamMember.league_rank();
      OutputScratchView legendre_field_values_at_point, jacobi_values_at_point;
      if (fad_size_output_ > 0) {
        legendre_field_values_at_point = OutputScratchView(teamMember.team_shmem(), polyOrder_ + 1, fad_size_output_);
        jacobi_values_at_point         = OutputScratchView(teamMember.team_shmem(), polyOrder_ + 1, fad_size_output_);
      }
      else {
        legendre_field_values_at_point = OutputScratchView(teamMember.team_shmem(), polyOrder_ + 1);
        jacobi_values_at_point         = OutputScratchView(teamMember.team_shmem(), polyOrder_ + 1);
      }
      
      const auto & x = inputPoints_(pointOrdinal,0);
      const auto & y = inputPoints_(pointOrdinal,1);
      
      // write as barycentric coordinates:
      const PointScalar lambda[3]    = {1. - x - y, x, y};
      
      switch (opType_)
      {
        case OPERATOR_VALUE:
        {
          // face functions
          {
            const PointScalar tLegendre = lambda[0] + lambda[1];
            Polynomials::shiftedScaledLegendreValues(legendre_field_values_at_point, polyOrder_, lambda[1], tLegendre);

            int fieldOrdinalOffset = 0;
            const int max_ij_sum = polyOrder_;
            for (int ij_sum=0; ij_sum<=max_ij_sum; ij_sum++)
            {
              for (int i=0; i<=ij_sum; i++)
              {
                const int j = ij_sum - i;
                const auto & legendreValue = legendre_field_values_at_point(i);
                const double alpha = i*2.0+1;
                
                const PointScalar tJacobi = 1.0;// lambda[0] + lambda[1] + lambda[2];
                Polynomials::shiftedScaledJacobiValues(jacobi_values_at_point, alpha, polyOrder_, lambda[2], tJacobi);
                
                const auto & jacobiValue = jacobi_values_at_point(j);
                output_(fieldOrdinalOffset,pointOrdinal) = legendreValue * jacobiValue;
                fieldOrdinalOffset++;
              }
            }
          }
        } // end OPERATOR_VALUE
          break;
        default:
          // unsupported operator type
          device_assert(false);
      }
    }
    
    // Provide the shared memory capacity.
    // This function takes the team_size as an argument,
    // which allows team_size-dependent allocations.
    size_t team_shmem_size (int team_size) const
    {
      // TODO: edit this to match scratch that we actually need.  (What's here is copied from H^1 basis on triangles…)
      // we will use shared memory to create a fast buffer for basis computations
      size_t shmem_size = 0;
      if (fad_size_output_ > 0)
        shmem_size += 2 * OutputScratchView::shmem_size(polyOrder_ + 1, fad_size_output_);
      else
        shmem_size += 2 * OutputScratchView::shmem_size(polyOrder_ + 1);
      
      return shmem_size;
    }
  };
  
  template<typename DeviceType,
           typename OutputScalar = double,
           typename PointScalar  = double>
  class LegendreBasis_HVOL_TRI
  : public Basis<DeviceType,OutputScalar,PointScalar>
  {
  public:
    using BasisBase = Basis<DeviceType,OutputScalar,PointScalar>;
    using HostBasis = LegendreBasis_HVOL_TRI<typename Kokkos::HostSpace::device_type,OutputScalar,PointScalar>;

    using typename BasisBase::OrdinalTypeArray1DHost;
    using typename BasisBase::OrdinalTypeArray2DHost;

    using typename BasisBase::OutputViewType;
    using typename BasisBase::PointViewType;
    using typename BasisBase::ScalarViewType;

    using typename BasisBase::ExecutionSpace;

  protected:
    int polyOrder_; // the maximum order of the polynomial
    EPointType pointType_;
  public:
    LegendreBasis_HVOL_TRI(int polyOrder, const EPointType pointType=POINTTYPE_DEFAULT)
    :
    polyOrder_(polyOrder),
    pointType_(pointType)
    {
      INTREPID2_TEST_FOR_EXCEPTION(pointType!=POINTTYPE_DEFAULT,std::invalid_argument,"PointType not supported");

      this->basisCardinality_     = ((polyOrder+2) * (polyOrder+1)) / 2;
      this->basisDegree_          = polyOrder;
      this->basisCellTopologyKey_ = shards::Triangle<>::key;
      this->basisType_            = BASIS_FEM_HIERARCHICAL;
      this->basisCoordinates_     = COORDINATES_CARTESIAN;
      this->functionSpace_        = FUNCTION_SPACE_HVOL;
      
      const int degreeLength = 1;
      this->fieldOrdinalPolynomialDegree_ = OrdinalTypeArray2DHost("Legendre H(vol) triangle polynomial degree lookup", this->basisCardinality_, degreeLength);
      this->fieldOrdinalH1PolynomialDegree_ = OrdinalTypeArray2DHost("Legendre H(grad) line polynomial degree lookup",  this->basisCardinality_, degreeLength);
      
      int fieldOrdinalOffset = 0;
      // **** face functions **** //
      const int max_ij_sum = polyOrder;
      for (int ij_sum=0; ij_sum<=max_ij_sum; ij_sum++)
      {
        for (int i=0; i<=ij_sum; i++)
        {
          const int j = ij_sum - i;
          this->fieldOrdinalPolynomialDegree_  (fieldOrdinalOffset,0) = i+j;
          this->fieldOrdinalH1PolynomialDegree_(fieldOrdinalOffset,0) = i+j+1;  // H^1 degree is one greater
          fieldOrdinalOffset++;
        }
      }
      INTREPID2_TEST_FOR_EXCEPTION(fieldOrdinalOffset != this->basisCardinality_, std::invalid_argument, "Internal error: basis enumeration is incorrect");
      
      // initialize tags
      {
        const auto & cardinality = this->basisCardinality_;
        
        // Basis-dependent initializations
        const ordinal_type tagSize  = 4;        // size of DoF tag, i.e., number of fields in the tag
        const ordinal_type posScDim = 0;        // position in the tag, counting from 0, of the subcell dim
        const ordinal_type posScOrd = 1;        // position in the tag, counting from 0, of the subcell ordinal
        const ordinal_type posDfOrd = 2;        // position in the tag, counting from 0, of DoF ordinal relative to the subcell
        
        OrdinalTypeArray1DHost tagView("tag view", cardinality*tagSize);
        const int faceDim = 2;

        for (ordinal_type i=0;i<cardinality;++i) {
          tagView(i*tagSize+0) = faceDim;     // face dimension
          tagView(i*tagSize+1) = 0;           // face id
          tagView(i*tagSize+2) = i;           // local dof id
          tagView(i*tagSize+3) = cardinality; // total number of dofs on this face
        }
        
        // Basis-independent function sets tag and enum data in tagToOrdinal_ and ordinalToTag_ arrays:
        // tags are constructed on host
        this->setOrdinalTagData(this->tagToOrdinal_,
                                this->ordinalToTag_,
                                tagView,
                                this->basisCardinality_,
                                tagSize,
                                posScDim,
                                posScOrd,
                                posDfOrd);
      }
    }
    
    const char* getName() const override {
      return "Intrepid2_LegendreBasis_HVOL_TRI";
    }
    
    virtual bool requireOrientation() const override {
      return false;
    }

    // since the getValues() below only overrides the FEM variant, we specify that
    // we use the base class's getValues(), which implements the FVD variant by throwing an exception.
    // (It's an error to use the FVD variant on this basis.)
    using BasisBase::getValues;
    
    virtual void getValues( OutputViewType outputValues, const PointViewType inputPoints,
                           const EOperator operatorType = OPERATOR_VALUE ) const override
    {
      auto numPoints = inputPoints.extent_int(0);
      
      using FunctorType = Hierarchical_HVOL_TRI_Functor<DeviceType, OutputScalar, PointScalar, OutputViewType, PointViewType>;
      
      FunctorType functor(operatorType, outputValues, inputPoints, polyOrder_);
      
      const int outputVectorSize = getVectorSizeForHierarchicalParallelism<OutputScalar>();
      const int pointVectorSize  = getVectorSizeForHierarchicalParallelism<PointScalar>();
      const int vectorSize = std::max(outputVectorSize,pointVectorSize);
      const int teamSize = 1; // because of the way the basis functions are computed, we don't have a second level of parallelism...

      auto policy = Kokkos::TeamPolicy<ExecutionSpace>(numPoints,teamSize,vectorSize);
      Kokkos::parallel_for("Hierarchical_HVOL_TRI_Functor", policy, functor);
    }

    BasisPtr<DeviceType,OutputScalar,PointScalar>
      getSubCellRefBasis(const ordinal_type subCellDim, const ordinal_type subCellOrd) const override{
      // no subcell ref basis for HVOL
      INTREPID2_TEST_FOR_EXCEPTION(true,std::invalid_argument,"Input parameters out of bounds");
    }

    virtual BasisPtr<typename Kokkos::HostSpace::device_type, OutputScalar, PointScalar>
    getHostBasis() const override {
      using HostDeviceType = typename Kokkos::HostSpace::device_type;
      using HostBasisType  = LegendreBasis_HVOL_TRI<HostDeviceType, OutputScalar, PointScalar>;
      return Teuchos::rcp( new HostBasisType(polyOrder_, pointType_) );
    }
  };
} // end namespace Intrepid2

#endif /* Intrepid2_LegendreBasis_HVOL_TRI_h */