On the Approximation of Spectra and Pseudospectra of Linear Operators on Hilbert Spaces


We present several new techniques for approximating spectra and pseudospectra of linear operators (not necessarily bounded) on a separable Hilbert space. This includes new results on the finite section method (and some variants of it) as well a generalization of the QR algorithm to infinite dimensions. In order to approximate spectra of arbitrary closed… (More)