text: 
  class Coeff{
      double xi;
      double xm;
      double deltaX_m;
      double deltaX_p;
  public:
      double beta;
      double gamma;
  
  	double alpha;
  	double f_theta;
  	double K0;
  	double K1;
  	double Kb;
  	double dB;
  	double dY;
      int n;
  	double* aA = nullptr;
  	double* bA = nullptr;
  	double* cA = nullptr;
  	double* aB = nullptr;
  	double* bB = nullptr;
  	double* cB = nullptr;
  	double* aY = nullptr;
  	double* bY = nullptr;
  	double* cY = nullptr;
  	double* d = nullptr;
  	double* XX = nullptr;
  	double* dx = nullptr;
  	double* fx = nullptr;
  	double** A = nullptr;
  	double** J = nullptr;
  	Coeff(double maxX, double K0_input, double K1_input,double Kb_input, double deltaT, double alpha_input, double gamma, double dB_input, double dY_input);
      ~Coeff();
      void calc_n(double dx);
  	void ini_jacob();
  	void ini_fx();
  	void ini_dx();
  	void calc_fx(double* x,double Theta);
  	void negative_fx();
  	void calc_jacob(double* x, double Theta);
      void Acalc_abc(double deltaT, double Theta, double deltaX);
  	void Bcalc_abc(double deltaT, double Theta, double deltaX);
  	void Ycalc_abc(double deltaT, double Theta, double deltaX);
  	void Allcalc_abc(double deltaT, double Theta, double deltaX);
      void get_XX(double *xx);
      void update(double* x, double Theta, double deltaX,double concA, double concB, double concC);
  	void xupdate(double* x);
  	double avg_dx();
  	double max_dx();
  };