1 MatrixXd X = MatrixXd::Random(5,5); 2 MatrixXd A = X + X.transpose(); 3 cout << "Here is a random symmetric 5x5 matrix:" << endl << A << endl << endl; 4 5 VectorXd diag(5); 6 VectorXd subdiag(4); 7 VectorXd hcoeffs(4); // Scratch space for householder reflector. 8 internal::tridiagonalization_inplace(A, diag, subdiag, hcoeffs, true); 9 cout << "The orthogonal matrix Q is:" << endl << A << endl; 10 cout << "The diagonal of the tridiagonal matrix T is:" << endl << diag << endl; 11 cout << "The subdiagonal of the tridiagonal matrix T is:" << endl << subdiag << endl; 12