/*
 * Definition of type for 3D vectors:  struct and some functions that
 * seem useful.
 *
 * (By putting this in a separate file we can potentially use it in many
 * programs.)
 */
#include <stdio.h>
#include <math.h>

typedef struct {
	double x;
	double y;
	double z;
} three_d_vec;

/* macro to square a number */
#define SQUARE(x) (x)*(x)

three_d_vec vec_add(three_d_vec v1, three_d_vec v2) {
	three_d_vec result = { v1.x + v2.x, v1.y + v2.y, v1.z + v2.z };
	return result;
}

three_d_vec vec_scalar_mult(double d, three_d_vec v1) {
	three_d_vec result = { d * v1.x, d * v1.y, d * v1.z };
	return result;
}

void vec_print(three_d_vec v1, FILE * outfile) {
	fprintf(stdout, "(%f %f %f)", v1.x, v1.y, v1.z);
}

double vec_length(three_d_vec v1) {
	return sqrt(SQUARE(v1.x) + SQUARE(v1.y) + SQUARE(v1.z));
}

/* 
 * FIXME:
 * add dot and cross products?
 */
double vec_dot_product(three_d_vec v1, three_d_vec v2);

three_d_vec vec_cross_product(three_d_vec v1, three_d_vec v2);