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

std::cout << "A fixed-size array:\n";
Array33f a1 = Array33f::Zero();
std::cout << a1 << "\n\n";

std::cout << "A one-dimensional dynamic-size array:\n";
ArrayXf a2 = ArrayXf::Zero(3);
std::cout << a2 << "\n\n";

std::cout << "A two-dimensional dynamic-size array:\n";
ArrayXXf a3 = ArrayXXf::Zero(3, 4);
std::cout << a3 << "\n";