128     pair_t px{1, 2};  in TEST()  local
131     std::cout << "px=" << px << " py=" << py << " px+py=" << (px + py) << "\n";  in TEST()
132     std::cout << "px=" << px << " py=" << py << " px*py=" << (px * py) << "\n";  in TEST()
133     std::cout << "px=" << px << " z="  << z  << " px+z="  << (px + z) << "\n";  in TEST()
134     std::cout << "px=" << px << " z="  << z  << " px*z="  << (px * z) << "\n";  in TEST()
135     std::cout << "px=" << px << " py=" << py << " innerProduct(px, py)="  in TEST()
136             << innerProduct(px, py) << "\n";  in TEST()
137     std::cout << "px=" << px << " py=" << py << " outerProduct(px, py)="  in TEST()
138             << outerProduct(px, py) << "\n";  in TEST()
148     std::cout << "ax=" << px << " ay=" << ay << " innerProduct(ax, ay)="  in TEST()
150     std::cout << "ax=" << px << " ay=" << ay << " outerProduct(ax, ay)="  in TEST()