Abstract:
The computation of the eigenvalue decomposition of matrices is one of the most investigated problems in numerical linear algebra. In particular, real nonsymmetric tridiagonal eigenvalue problems arise in a variety of applications. In this paper the problem of computing an eigenvector corresponding to a known eigenvalue of a real nonsymmetric tridiagonal matrix is considered, developing an algorithm that combines part of a $QR$ sweep and part of a $QL$ sweep, both with the shift equal to the known eigenvalue. The numerical tests show the reliability of the proposed method.