Location of matrix eigenvalues in the complex plane
Stephanie J. Barnett, R. E. Scraton · IEEE Transactions on Automatic Control · 1982
LetSbe a region which can be mapped into a standard regionRof the complex plane (unit circle or half-plane) by a rational transformation. Then the problem of locating the eigenvalues ofArelative toScan be transformed into that for an appropriate block companion matrix relative toR.