gauss_legendre_trapezoid.cc

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#include "quadrature/angular/gauss_legendre_trapezoid.h"
 
#include <cmath>
namespace hummingbird {
GaussLegendreTrapezoid::GaussLegendreTrapezoid(const size_t n_azim,
                                               const size_t n_polar,
                                               const bool polar_measured_from_x) {
  abscissas_.reserve(n_azim * n_polar);
  GaussLegendre gl_polar_quad(n_polar);
 
  double delta_azim = 2.0 * M_PI / (static_cast<double>(n_azim));
  size_t counter = 0;
  for (auto i = 0; i < n_polar; i++) {
    double polar = gl_polar_quad.GetAbscissa(i);
    for (double j = 0; j < n_azim; j++) {
      double azim = -M_PI + j * delta_azim;
 
      Ordinate new_ordinate = polar_measured_from_x
          ? Ordinate(std::acos(polar), M_PI / 2.0)
          : Ordinate(azim, std::acos(polar));
      abscissas_.push_back(std::move(new_ordinate));
 
      double weight = gl_polar_quad.GetWeight(i) * delta_azim;
      weight_map_.insert({counter, weight});
      counter++;
    }
  }
}
}  // namespace hummingbird