MatrixXi m(2, 2); m << 1, 0, 1, 1; cout << "Comparing m with identity matrix:" << endl; cout << m.cwiseEqual(MatrixXi::Identity(2, 2)) << endl; Index count = m.cwiseEqual(MatrixXi::Identity(2, 2)).count(); cout << "Number of coefficients that are equal: " << count << endl;