1 RowVector4i v = RowVector4i::Random(); 2 cout << "Here is the vector v:" << endl << v << endl; 3 cout << "Here is v.head(2):" << endl << v.head<2>() << endl; 4 v.head<2>().setZero(); 5 cout << "Now the vector v is:" << endl << v << endl; 6