#define IS ==
#define ISNT !=

typedef double (*func_to_solve_t) (double);
extern double solve_func (func_to_solve_t fn, double goal, double guess);

inline double max (const double &a, const double &b) { return (a >= b ? a : b); }
inline double min (const double &a, const double &b) { return (a <= b ? a : b); }

inline double abs (const double &a) { return (fabs (a)); }
inline long abs (const long &a) { return (a >= 0 ? a : -a); }

extern FILE *log_file;
extern bool logging;

#define db_printf if (!logging) {} else fprintf