FastDeploy/third_party/eigen/doc/snippets/Tutorial_AdvancedInitialization_Block.cpp

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;