Perturbation Bounds For Matrix Eigenvalues PDF Download

Abstract: "There is now a large literature on structured perturbation bounds for eigenvalue problems of the form [formula], where H and M are Hermitian. These results give relative error bounds on the i[superscript th] eigenvalue, [lambda subscript i], of the form [formula], and bound the error in the i[superscript th] eigenvector in terms of the relative gap, [formula]. In general, this theory usually restricts H to be nonsingular and M to be positive definite. We relax this restriction by allowing H to be singular. For our results on eigenvales we allow M to be positive semi-definite and for few results we allow it to be more general. For these problems, for eigenvalues that are not zero or infinity under perturbation, it is possible to obtain local relative error bounds. Thus, a wider class of problems may be characterized by this theory. The theory is applied to the SVD and some of its generalizations. In fact, for structured perturbations, our bound on generalized Hermitian eigenproblems are based upon our bounds for generalized singular value problems. Although it is impossible to give meaningful relative error bounds on eigenvalues that are not bounded away from zero, we show that the error in the subspace associated with those eigenvalues can be characterized meaningfully."