1*bf2c3715SXin Li RowVector4i v = RowVector4i::Random(); 2*bf2c3715SXin Li cout << "Here is the vector v:" << endl << v << endl; 3*bf2c3715SXin Li cout << "Here is v.head(2):" << endl << v.head(2) << endl; 4*bf2c3715SXin Li v.head(2).setZero(); 5*bf2c3715SXin Li cout << "Now the vector v is:" << endl << v << endl; 6