The Gerschgorin discs under unitary similarity
Volume 38 / 1997
Banach Center Publications 38 (1997), 427-441
DOI: 10.4064/-38-1-427-441
Abstract
The intersection of the Gerschgorin regions over the unitary similarity orbit of a given matrix is studied. It reduces to the spectrum in some cases: for instance, if the matrix satisfies a quadratic equation, and also for matrices having "large" singular values or diagonal entries. This leads to a number of open questions.
