#include <iostream>

void mat_identity(double m[9]) {
    for (int i = 0; i < 9; i++) m[i] = 0.0;
    m[0] = m[4] = m[8] = 1.0;
}

void mat_print(double m[9]) {
    for (int r = 0; r < 3; r++) {
        std::cout << "| " << m[r*3] << " " << m[r*3+1] << " " << m[r*3+2] << " |\n";
    }
}