text: #ifndef _TRON_H
  #define _TRON_H
  
  class function
  {
  public:
  	virtual double fun(double *w) = 0 ;
  	virtual void grad(double *w, double *g) = 0 ;
  	virtual void Hv(double *s, double *Hs) = 0 ;
  
  	virtual int get_nr_variable(void) = 0 ;
  	virtual ~function(void){}
  };
  
  class TRON
  {
  public:
  	TRON(const function *fun_obj, double eps = 0.1, double eps_cg = 0.1, int max_iter = 1000);
  	~TRON();
  
  	void tron(double *w);
  	void set_print_string(void (*i_print) (const char *buf));
  
  private:
  	int trcg(double delta, double *g, double *s, double *r, bool *reach_boundary);
  	double norm_inf(int n, double *x);
  
  	double eps;
  	double eps_cg;
  	int max_iter;
  	function *fun_obj;
  	void info(const char *fmt,...);
  	void (*tron_print_string)(const char *buf);
  };
  #endif
  