#include <triqs/arrays.hpp>
using namespace triqs;
int main() {
 // declare and init a matrix
 clef::placeholder<0> i_;
 clef::placeholder<1> j_;
 arrays::matrix<int> A(2, 2);
 A(i_, j_) << i_ + j_;

 // the mapped function
 auto F = arrays::map([](int i) { return i * 2.5; });

 std::cout << "A = " << A << std::endl;
 std::cout << "F(A) = " << F(A) << std::endl; // oops no computation done
 std::cout << "F(A) = " << make_matrix(F(A)) << std::endl;
 std::cout << "3*F(2*A) = " << make_matrix(3 * F(2 * A)) << std::endl;
}