#include <Eigen/Dense>
#include <iostream>

using namespace Eigen;
using namespace std;

int main() {
  ArrayXXf a(2, 2);
  ArrayXXf b(2, 2);
  a << 1, 2, 3, 4;
  b << 5, 6, 7, 8;
  cout << "a * b = " << endl << a * b << endl;
}