#include <triqs/arrays.hpp>
using triqs::arrays::matrix;
using triqs::clef::placeholder;
int main() {
 // declare an init 2 matrices
 placeholder<0> i_;
 placeholder<1> j_;
 matrix<double> A(2, 2), B(2, 2), C;
 A(i_, j_) << i_ + j_;
 B(i_, j_) << 2 * i_ + j_;
 C = A * B;
 std::cout << " C = " << C << std::endl;
}