直接贴代码吧，使用的MatrixXd 和<<运算符：

int main(int argc, char *argv[])
{Eigen::MatrixXd B(2, 2);B << 1, 2,3, 4;Eigen::MatrixXd C(2, 2);C << 5, 6,7, 8;Eigen::MatrixXd D(2, 2);D << 9, 10,11, 12;Eigen::MatrixXd H(2, 2);H << 13, 14,15, 16;// Horizontal concatenation of B and CEigen::MatrixXd upper(B.rows(), B.cols() + C.cols());upper << B, C;std::cout << "Combined Matrix upper:\n" << upper << std::endl;// Horizontal concatenation of D and HEigen::MatrixXd lower(D.rows()+ H.rows(), D.cols());lower << D,H;std::cout << "Combined Matrix lower:\n" << lower << std::endl;// Vertical concatenation of upper and lowerEigen::MatrixXd A(B.rows() + D.rows(), B.cols() + C.cols());A << B, C,D, H;std::cout << "Combined Matrix A:\n" << A << std::endl;return 0;
}

效果如图