Oreo  |  8.0.0_r4
C++程序  |  6行  |  132 B 

MatrixXf matA(2, 2);
matA << 1, 2, 3, 4;
MatrixXf matB(4, 4);
matB << matA, matA/10, matA/10, matA;
std::cout << matB << std::endl;