The problem considered is to give bounds for finite perturbations of simple and multiple eigenvalues &lgr;i of nonnormal matrices, where these bounds are in terms of the eigenvalues {&lgr;i}, the departure from normality &sgr;, and the Frobenius norm ‖ &Dgr;A ‖ F of the perturbation matrix, but not in terms of the eigensystem. The bounds which are derived are shown to be almost attainable for any set of all matrices of given {&lgr;i} and &sgr;. One conclusion is that, very roughly speaking, a simple eigenvalue &lgr;1 is perturbed by |&Dgr;&lgr;1| ≲ ‖ &Dgr;A ‖F · ∏ (&sgr;/&thgr;j) where &thgr;j is of the order of magnitude of |&lgr;1 - &lgr;j|, the product being extended over all j where &thgr;j ≲ &sgr;.
The Latest from CACM
Shape the Future of Computing
ACM encourages its members to take a direct hand in shaping the future of the association. There are more ways than ever to get involved.
Get InvolvedCommunications of the ACM (CACM) is now a fully Open Access publication.
By opening CACM to the world, we hope to increase engagement among the broader computer science community and encourage non-members to discover the rich resources ACM has to offer.
Learn More
Join the Discussion (0)
Become a Member or Sign In to Post a Comment