integrator_4D_finiteTx0_cpu.hh

Go to the documentation of this file.

#pragma once
 
// standard library
#include <future>
 
// external libraries
#include <tbb/tbb.h>
 
// DiFfRG
#include <DiFfRG/common/quadrature/quadrature_provider.hh>
 
namespace DiFfRG
{
  template <typename NT, typename KERNEL> class Integrator4DFiniteTx0TBB
  {
  public:
    using ctype = typename get_type::ctype<NT>;
 
    Integrator4DFiniteTx0TBB(QuadratureProvider &quadrature_provider, const std::array<uint, 4> grid_sizes,
                             const ctype x_extent, const ctype x0_extent, const uint x0_summands, const JSONValue &json)
        : Integrator4DFiniteTx0TBB(quadrature_provider, grid_sizes, x_extent, x0_extent, x0_summands,
                                   json.get_double("/physical/T"), json.get_uint("/integration/cudathreadsperblock"))
    {
    }
 
    Integrator4DFiniteTx0TBB(QuadratureProvider &quadrature_provider, std::array<uint, 4> _grid_sizes,
                             const ctype x_extent, const ctype x0_extent, const uint _x0_summands, const ctype T,
                             const uint max_block_size = 0)
        : quadrature_provider(quadrature_provider),
          grid_sizes{{_grid_sizes[0], _grid_sizes[1], _grid_sizes[2], _grid_sizes[3] + _x0_summands}},
          x_extent(x_extent), x0_extent(x0_extent), original_x0_summands(_x0_summands), m_T(T)
    {
      ptr_x_quadrature_p = quadrature_provider.get_points(grid_sizes[0]).data();
      ptr_x_quadrature_w = quadrature_provider.get_weights(grid_sizes[0]).data();
      ptr_ang_quadrature_p = quadrature_provider.get_points(grid_sizes[1]).data();
      ptr_ang_quadrature_w = quadrature_provider.get_weights(grid_sizes[1]).data();
 
      set_T(T);
 
      (void)max_block_size;
    }
 
    void set_T(const ctype T)
    {
      m_T = T;
      if (is_close(T, 0.))
        x0_summands = 0;
      else
        x0_summands = original_x0_summands;
      ptr_x0_quadrature_p = quadrature_provider.get_points<ctype>(grid_sizes[3] - x0_summands).data();
      ptr_x0_quadrature_w = quadrature_provider.get_weights<ctype>(grid_sizes[3] - x0_summands).data();
    }
 
    void set_x0_extent(const ctype val) { x0_extent = val; }
 
    Integrator4DFiniteTx0TBB(const Integrator4DFiniteTx0TBB &other)
        : quadrature_provider(other.quadrature_provider), grid_sizes(other.grid_sizes),
          ptr_x_quadrature_p(other.ptr_x_quadrature_p), ptr_x_quadrature_w(other.ptr_x_quadrature_w),
          ptr_ang_quadrature_p(other.ptr_ang_quadrature_p), ptr_ang_quadrature_w(other.ptr_ang_quadrature_w),
          ptr_x0_quadrature_p(other.ptr_x0_quadrature_p), ptr_x0_quadrature_w(other.ptr_x0_quadrature_w),
          x_extent(other.x_extent), x0_extent(other.x0_extent), original_x0_summands(other.x0_summands),
          x0_summands(other.x0_summands), m_T(other.m_T)
    {
    }
 
    template <typename... T> NT get(const ctype k, const T &...t) const
    {
      constexpr int d = 4;
      using std::sqrt, std::exp, std::log;
 
      const ctype integral_start = (2 * x0_summands * (ctype)M_PI * m_T) / k;
      const ctype log_start = log(integral_start + (m_T == 0) * ctype(1e-3));
      const ctype log_ext = log(x0_extent / (integral_start + (m_T == 0) * ctype(1e-3)));
 
      const auto constant = KERNEL::constant(k, t...);
      return constant +
             tbb::parallel_reduce(
                 tbb::blocked_range3d<uint, uint, uint>(0, grid_sizes[0], 0, grid_sizes[1], 0, grid_sizes[2]), NT(0),
                 [&](const tbb::blocked_range3d<uint, uint, uint> &r, NT value) -> NT {
                   for (uint idx_x = r.pages().begin(); idx_x != r.pages().end(); ++idx_x) {
                     const ctype q = k * sqrt(ptr_x_quadrature_p[idx_x] * x_extent);
                     for (uint idx_y = r.rows().begin(); idx_y != r.rows().end(); ++idx_y) {
                       const ctype cos = 2 * (ptr_ang_quadrature_p[idx_y] - (ctype)0.5);
                       for (uint idx_z = r.cols().begin(); idx_z != r.cols().end(); ++idx_z) {
                         const ctype phi = 2 * (ctype)M_PI * ptr_ang_quadrature_p[idx_z];
 
                         const ctype weight = 2 * (ctype)M_PI * ptr_ang_quadrature_w[idx_z] * 2 *
                                              ptr_ang_quadrature_w[idx_y] * ptr_x_quadrature_w[idx_x] * x_extent;
 
                         // integral
                         const ctype int_element_int =
                             (powr<d - 3>(q) / (ctype)2 * powr<2>(k)) // x = p^2 / k^2 integral
                             * (k)                                    // x0 = q0 / k integral
                             / powr<d>(2 * (ctype)M_PI);              // fourier factor
                         for (uint idx_0 = 0; idx_0 < grid_sizes[3] - x0_summands; ++idx_0) {
                           const ctype q0 =
                               k * (exp(log_start + log_ext * ptr_x0_quadrature_p[idx_0]) - (m_T == 0) * ctype(1e-3));
                           const ctype m_weight = weight * (ptr_x0_quadrature_w[idx_0] * log_ext * q0 / k);
 
                           value +=
                               int_element_int * m_weight *
                               (KERNEL::kernel(q, cos, phi, q0, k, t...) + KERNEL::kernel(q, cos, phi, -q0, k, t...));
                         }
 
                         // sum
                         const ctype int_element_sum =
                             m_T                                        // solid nd angle
                             * (powr<d - 3>(q) / (ctype)2 * powr<2>(k)) // x = p^2 / k^2 integral
                             / powr<d - 1>(2 * (ctype)M_PI);            // fourier factor
 
                         for (uint idx_0 = 0; idx_0 < x0_summands; ++idx_0) {
                           const ctype q0 = 2 * (ctype)M_PI * m_T * idx_0;
                           value += int_element_sum * weight *
                                    (idx_0 == 0 ? KERNEL::kernel(q, cos, phi, (ctype)0, k, t...)
                                                : KERNEL::kernel(q, cos, phi, q0, k, t...) +
                                                      KERNEL::kernel(q, cos, phi, -q0, k, t...));
                         }
                       }
                     }
                   }
                   return value;
                 },
                 [&](NT x, NT y) -> NT { return x + y; });
    }
 
    template <typename... T> std::future<NT> request(const ctype k, const T &...t) const
    {
      return std::async(std::launch::deferred, [=, this]() { return get(k, t...); });
    }
 
  private:
    QuadratureProvider &quadrature_provider;
 
    std::array<uint, 4> grid_sizes;
 
    const ctype x_extent;
    ctype x0_extent;
    const uint original_x0_summands;
    uint x0_summands;
    ctype m_T;
 
    const ctype *ptr_x_quadrature_p;
    const ctype *ptr_x_quadrature_w;
    const ctype *ptr_ang_quadrature_p;
    const ctype *ptr_ang_quadrature_w;
    const ctype *ptr_x0_quadrature_p;
    const ctype *ptr_x0_quadrature_w;
  };
} // namespace DiFfRG