#define NCOLORS 3
#define HUGE 1e15
#define EPSILON 1e-3

struct vector
    {
    double x;
    double y;
    double z;
    double l;
    double xzl;
    } ;

struct ray
    {
    struct vector org;
    struct vector dir;
    } ;

struct sphere
    {
    struct vector cent;
    double rad;
    } ;

struct ball
    {
    struct sphere s;
    double ior;
    double rfr;
    double rfl;
    double dif;
    double amb;
    double red;
    double green;
    double blue;
    struct vector v;
    };

struct mat
    {
    struct vector x;  	/* first !row! */
    struct vector y;  	/*second !row! */
    struct vector z;	 /* third !row! */
    };