On eigenvalues of complex matrices in a sector
Brian D. O. Anderson, N.K. Bose, E.I. Jury · IEEE Transactions on Automatic Control · 1975
It is shown that the test to determine whether all eigenvalues of a complex matrix of ordernlie in a certain sector can be replaced by an equivalent test to find whether all eigenvalues of a real matrix of order4nlie in the left haft plane.