Matrix4d X = Matrix4d::Random(4,4); Matrix4d A = X + X.transpose(); cout << "Here is a random symmetric 4x4 matrix:" << endl << A << endl; Tridiagonalization<Matrix4d> triOfA(A); Vector3d hc = triOfA.householderCoefficients(); cout << "The vector of Householder coefficients is:" << endl << hc << endl;