IP 2

IP 2. An envelope for the spectrum of a matrix
Chair: Steve Kirkland

An envelope-type region E(A) in the complex plane that contains the eigenvalues of a given n × n complex matrix A is introduced. E(A) is the intersection of an infinite number of regions defined by cubic curves. The notion and method of construction of E(A) extend those of the numerical range of A, which is known to be an intersection of an infinite number of half-planes; as a consequence, E(A) is contained in the numerical range and represents an improvement in localizing the spectrum of A.
Michael Tsatsomeros
Dept. of Mathematics, Washington State University, US