const_velocity_spline.h

/*
 * vev_spline.cpp
 *
 * cubic spline interpolation for path in VEV space using constant speed (in
 * particular = 1)
 *
 * We use the lib spline.h to make a spline in each direction, the parameter is
 * the linear length between the points (not important as long as it
 * monotonically increasing) Then we make a thoroughly integration (Simpson 3/8
 * rule) to convert from linear length to spline length, and vice-versa.
 * Interpolate using a spline
 *
 */
 
#pragma once
 
#include <BSMPT/utility/Logger.h> // for Logger Class
#include <BSMPT/utility/spline/spline.h>
#include <BSMPT/utility/utility.h>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <sstream>
 
class cvspline
{
private:
  std::vector<double> list_x;
  std::vector<double> list_l;
 
  double lin_abs_deriv(double x);
 
  double Simpson_step(double t0, double t1);
 
public:
  int dim;
  int num_points;
  int num_inter;
  tk::spline x_to_l;
  tk::spline l_to_x;
  float linL;
  float L;
  std::vector<double> lin_lengths;
  std::vector<double> vev_position;
  std::vector<tk::spline> splines;
  std::vector<std::vector<double>> transposed_phi;
  std::vector<std::vector<double>> phipath;
  cvspline();
  cvspline(const std::vector<std::vector<double>> &phipath_in);
  cvspline(const std::vector<std::vector<double>> &phipath_in,
           int input_num_inter);
  void initialize();
  void add_point(const double &p,
                 const std::vector<double> &new_vev,
                 const bool &compile = true);
  std::vector<double> deriv(int order, double x);
  std::vector<double> dl(double l);
  std::vector<double> d2l(double l);
  std::vector<double> operator()(double l) const;
  void print_path() const;
  void save_path(const std::string &file_name, const bool &header = true);
};