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#include <stddef.h>
#include <stdio.h>
struct vec3 {
double x;
double y;
double z;
};
struct vec3 vec3_add(struct vec3 * const v, struct vec3 * const u)
{
struct vec3 result = {0, 0, 0};
if (v == NULL || u == NULL)
return result;
result.x = v->x + u->x;
result.y = v->y + u->y;
result.z = v->z + u->z;
return result;
}
struct vec3 vec3_mul(struct vec3 * const v, const double scalar)
{
struct vec3 result = {0, 0, 0};
if (v == NULL)
return result;
result.x = scalar * v->x;
result.y = scalar * v->y;
result.z = scalar * v->z;
return result;
}
struct vec3 vec3_sub(struct vec3 * const v, struct vec3 * const u)
{
struct vec3 result = {0, 0, 0};
result = vec3_mul(u, -1.0);
result = vec3_add(v, &result);
return result;
}
double vec3_dot(struct vec3 * const v, struct vec3 * const u)
{
if (v == NULL || u == NULL)
return 0;
return (v->x * u->x) + (v->y * u->y) + (v->z * u->y);
}
struct vec3 vec3_cross(struct vec3 * const v, struct vec3 * const u)
{
struct vec3 result = {0, 0, 0};
result.x = (v->y * u->z) - (v->z * u->y);
result.y = (v->z * u->x) - (v->x * u->z);
result.z = (v->x * u->y) - (v->y * u->x);
return result;
}
void vec3_print(struct vec3 * const v)
{
if (v == NULL)
return;
printf("<%.2f,%.2f,%.2f>\n", v->x, v->y, v->y);
}
int main(int argc, char *argv[])
{
struct vec3 a = {1, 2, 3};
struct vec3 b = {4, 5, 6};
struct vec3 res;
printf("a = ");
vec3_print(&a);
printf("b = ");
vec3_print(&b);
printf("sum a + b : ");
res = vec3_add(&a, &b);
vec3_print(&res);
printf("sub a - b : ");
res = vec3_sub(&a, &b);
vec3_print(&res);
printf("product 3*a : ");
res = vec3_mul(&a, 3);
vec3_print(&res);
printf("dot product : ");
printf("%.2f\n", vec3_dot(&a, &b));
printf("cross product : ");
res = vec3_cross(&a, &b);
vec3_print(&res);
return 0;
}
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