quadrature.hpp

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// --------------------------------------------------------------------------
//
// Copyright (C) 2025-present by Pablo Antolin
//
// This file is part of the QUGaR library.
//
// SPDX-License-Identifier:    MIT
//
// --------------------------------------------------------------------------
 
#ifndef QUGAR_LIBRARY_QUADRATURE_HPP
 
#define QUGAR_LIBRARY_QUADRATURE_HPP
 
 
 
#include <qugar/bbox.hpp>
#include <qugar/point.hpp>
#include <qugar/types.hpp>
 
#include <array>
#include <memory>
#include <type_traits>
 
 
namespace qugar {
 
 
class Gauss
{
public:
  static constexpr int n_max = 100;
 
  static real get_abscissa(const int n_points, const int pt_id);
 
  static real get_weight(const int n_points, const int pt_id);
 
 
private:
  static constexpr int n_entries = n_max * (n_max + 1);
 
  static const std::array<real, n_entries> &get_quad_data();
};
 
class TanhSinh
{
public:
  static constexpr int n_max = 100;
 
  static real get_abscissa(const int n_points, const int pt_id);
 
  static real get_weight(const int n_points, const int pt_id);
 
 
private:
  static constexpr int n_entries = n_max * (n_max + 1);
 
  static const std::array<real, n_entries> &get_quad_data();
};
 
template<int dim> class Quadrature
{
public:
  using Pt = Point<dim>;
 
  using Domain = std::conditional_t<dim == 1, Interval, BoundBox<dim>>;
 
 
  Quadrature() = delete;
 
  Quadrature(const std::vector<Pt> &points, const std::vector<real> &weights);
 
  [[nodiscard]] static std::shared_ptr<Quadrature> create_Gauss_01(int n_points);
 
  [[nodiscard]] static std::shared_ptr<Quadrature> create_Gauss_01(const std::array<int, dim> n_points);
 
  [[nodiscard]] static std::shared_ptr<Quadrature> create_Gauss(const std::array<int, dim> n_points,
    const Domain &domain);
 
  [[nodiscard]] static std::shared_ptr<Quadrature> create_tanh_sinh_01(int n_points);
 
  [[nodiscard]] static std::shared_ptr<Quadrature> create_tanh_sinh_01(const std::array<int, dim> n_points);
 
  [[nodiscard]] static std::shared_ptr<Quadrature> create_tanh_sinh(const std::array<int, dim> n_points,
    const Domain &domain);
 
  void scale_weights(const real ratio);
 
  [[nodiscard]] const std::vector<Pt> &points() const;
 
  [[nodiscard]] const std::vector<real> &weights() const;
 
  [[nodiscard]] std::vector<Pt> &points();
 
  [[nodiscard]] std::vector<real> &weights();
 
  [[nodiscard]] std::size_t get_num_points() const;
 
private:
  std::vector<Pt> points_;
  std::vector<real> weights_;
 
  template<typename QuadType>
  [[nodiscard]] static std::shared_ptr<Quadrature<dim>> create_tp_quadrature(const std::array<int, dim> n_points,
    const Domain &domain);
};
 
 
}// namespace qugar
 
#endif// QUGAR_LIBRARY_QUADRATURE_HPP