/* ----------------------------------------------------------------------
** Figure 23.8 The root.h header file.
*/
#ifndef ROOT
#define ROOT

/* Constants for root finders. ------------------------------------------ 
** Return when approximation is within EPS of root.               
*/
#define EPS 1.0e-4

/* Numbers with smaller magnitude than this will be treated as zero. 
*/
#define LIMIT 1.0e-10                                                      

/* Loop cutoff for secant method 
*/
#define MAX_ITER 50 

/* ----------------------------------------------------------------------
** error codes returned by the roots modules and used by main(). 
*/
typedef enum { 
    ROOT_OK, NO_ROOT, BAD_INITIAL_POINTS, HORIZONTAL, TOO_MANY_ITERATIONS 
} er_type;

/* ----------------------------------------------------------------------
** Table of error messages; used by main(). 
*/
static string const errmsg[] = { 
        "root found",
        "no root in interval",
        "initial points too close together",
        "secant almost horizontal",
        "iteration limit exceeded"
    };

/* ----------------------------------------------------------------------
** root-finding methods called by main().   
*/
er_type secant( double x1, double x2, double *rootp );
er_type bisect( double xlow, double xup, double *rootp );