/* vector.h: operations on vectors and points. */

#ifndef VECTOR_H
#define VECTOR_H

#include "point.h"
#include "exception.h"

/* Our vectors are represented as displacements along the x and y axes.  */

typedef struct
{
  float dx, dy, dz;
} vector_type;


/* Consider a point as a vector from the origin.  */
extern vector_type make_vector (const float_coord);

/* And a vector as a point, i.e., a displacement from the origin.  */
extern float_coord vector_to_point (const vector_type);


/* Definitions for these common operations can be found in any decent
   linear algebra book, and most calculus books.  */

extern float magnitude (const vector_type);
extern vector_type normalize (const vector_type);

extern vector_type Vadd (const vector_type, const vector_type);
extern float Vdot (const vector_type, const vector_type);
extern vector_type Vmult_scalar (const vector_type, const float);
extern float Vangle (const vector_type in, const vector_type out, at_exception_type * exp);

/* These operations could have been named `P..._vector' just as well as
   V..._point, so we may as well allow both names.  */
#define Padd_vector Vadd_point
extern float_coord Vadd_point
  (const float_coord, const vector_type);

#define Psubtract_vector Vsubtract_point
extern float_coord Vsubtract_point
  (const float_coord, const vector_type);

/* This returns the rounded sum.  */
#define IPadd_vector Vadd_int_point

pm_pixelcoord
Vadd_int_point(pm_pixelcoord const c,
               vector_type   const v);

/* Take the absolute value of both components.  */
extern vector_type Vabs (const vector_type);

/* Operations on points with real coordinates.  It is not orthogonal,
   but more convenient, to have the subtraction operator return a
   vector, and the addition operator return a point.  */
extern vector_type Psubtract
  (const float_coord, const float_coord);

vector_type
IPsubtract(pm_pixelcoord const coord1,
           pm_pixelcoord const coord2);

/* These are heavily used in spline fitting.  */
extern float_coord Padd (const float_coord,
                                  const float_coord);
extern float_coord Pmult_scalar (const float_coord, const float);

#endif