lammps/lib/kokkos/example/feint/feint.hpp

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//                        Kokkos v. 2.0
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#ifndef KOKKOS_EXAMPLE_FEINT_HPP
#define KOKKOS_EXAMPLE_FEINT_HPP

#include <iostream>
#include <BoxElemFixture.hpp>
#include <ElemFunctor.hpp>
#include <feint_fwd.hpp>

namespace Kokkos {
namespace Example {

/** \brief  Vector valued function to numerically integrate.
 *
 *  F(X) = { 1 , x , y , z , x*y , y*z , z*x , x*y*z }
 *
 *  Integrates on a unit cube to:
 *    { 1 , 1/2 , 1/2 , 1/2 , 1/4 , 1/4 , 1/4 , 1/8 }
 */
struct MyFunctionType {

  enum { value_count = 8 };

  // Evaluate function at coordinate.
  template< typename CoordType , typename ValueType >
  KOKKOS_INLINE_FUNCTION
  void operator()( const CoordType point[] , ValueType value[] ) const
    {
      value[0] = 1 ;
      value[1] = point[0] ;
      value[2] = point[1] ;
      value[3] = point[2] ;
      value[4] = point[0] * point[1] ;
      value[5] = point[1] * point[2] ;
      value[6] = point[2] * point[0] ;
      value[7] = point[0] * point[1] * point[2] ;
    }
};

template < class Device , bool UseAtomic >
void feint(
  const unsigned global_elem_nx ,
  const unsigned global_elem_ny ,
  const unsigned global_elem_nz )
{
  //----------------------------------------
  // Create the unstructured finite element mesh box fixture on the device:

  typedef Kokkos::Example::
    BoxElemFixture< Device , Kokkos::Example::BoxElemPart::ElemLinear >
    // BoxElemFixture< Device , Kokkos::Example::BoxElemPart::ElemQuadratic >
      BoxFixtureType ;

  // MPI distributed parallel domain decomposition of the fixture.
  // Either by element (DecomposeElem) or by node (DecomposeNode)
  // with ghosted elements.

  static const Kokkos::Example::BoxElemPart::Decompose
    decompose = Kokkos::Example::BoxElemPart:: DecomposeElem ;
    // decompose = Kokkos::Example::BoxElemPart:: DecomposeNode ;

  // Not using MPI in this example.
  const unsigned mpi_rank = 0 ;
  const unsigned mpi_size = 1 ;

  const BoxFixtureType fixture( decompose , mpi_size , mpi_rank ,
                                global_elem_nx ,
                                global_elem_ny ,
                                global_elem_nz );

  //----------------------------------------
  // Create and execute the numerical integration functor on the device:

  typedef Kokkos::Example::
    FiniteElementIntegration< BoxFixtureType , MyFunctionType , UseAtomic >
      FeintType ;

  const FeintType feint( fixture , MyFunctionType() );

  typename FeintType::value_type elem_integral ;

  // A reduction for the global integral:
  Kokkos::parallel_reduce( fixture.elem_count() , feint , elem_integral );

  if ( elem_integral.error ) {
    std::cout << "An element had a spatial jacobian error" << std::endl ;
    return ;
  }

  std::cout << "Elem integral =" ;
  for ( int i = 0 ; i < MyFunctionType::value_count ; ++i ) {
    std::cout << " " << elem_integral.value[i] ;
  }
  std::cout << std::endl ;
 
  //----------------------------------------
  // Create and execute the nodal lumped value projection and reduction functor:

  typedef Kokkos::Example::
    LumpElemToNode< typename FeintType::NodeValueType ,
                    typename FeintType::ElemValueType ,
                    UseAtomic > LumpType ;

  const LumpType lump( feint.m_node_lumped ,
                       feint.m_elem_integral ,
                       fixture.elem_node() );

  typename LumpType ::value_type node_sum ;

  Kokkos::parallel_reduce( fixture.node_count() , lump , node_sum );

  std::cout << "Node lumped sum =" ;
  for ( int i = 0 ; i < MyFunctionType::value_count ; ++i ) {
    std::cout << " " << node_sum.value[i] ;
  }
  std::cout << std::endl ;
}

} /* namespace Example */
} /* namespace Kokkos */

#endif /* #ifndef KOKKOS_EXAMPLE_FEINT_HPP */