Abstract
We prove new spectral enclosures for the non-real spectrum of a class of 2×2 block operator matrices with self-adjoint operators A and D on the diagonal and operators B and -B* as off-diagonal entries. One of our main results resembles Gershgorin's circle theorem. The enclosures are applied to J-frame operators.
Original language | English |
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Article number | 108455 |
Number of pages | 24 |
Journal | Journal of Functional Analysis |
Volume | 278 |
Issue number | 10 |
Early online date | 2 Jan 2020 |
DOIs | |
Publication status | Published - 1 Jun 2020 |
Keywords
- block operator matrix
- quadratic numerical range
- spectral enclosure
- Gershgorin's circle