On Eigenvalue and Eigenvector Estimates for Nonnegative Definite Operators
On Eigenvalue and Eigenvector Estimates for Nonnegative Definite Operators
We present a perturbation approach to the Rayleigh–Ritz approximations in the sense of Davis, Kahan, and Weinberger. We restrict ourselves to nonnegative definite self‐adjoint operators and obtain sharp bounds of relative type for both eigenvalues and eigenvectors. The operators are allowed to have nontrivial null‐spaces, and the test spaces need …