#include <iostream>

void vec_add(double[3], double[3], double[3]);
void vec_print(double[3]);
void mat_identity(double[9]);
void mat_print(double[9]);

int main() {
    double a[3] = {1, 2, 3};
    double b[3] = {4, 5, 6};
    double c[3];

    vec_add(a, b, c);
    std::cout << "vec_add: ";
    vec_print(c);

    double m[9];
    mat_identity(m);
    std::cout << "identity matrix:\n";
    mat_print(m);

    return 0;
}