eigen/doc/snippets/Tridiagonalization_decomposeInPlace.cpp
Antonio Sanchez 0d89012708 Update code snippet for tridiagonalize_inplace.
(cherry picked from commit fb1718ad14485ccf733d90807253e47c1f72e275)
2021-08-12 15:37:32 +00:00

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550 B
C++

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