Abstract
In algebraic function theory, there is a well established method which uses ‘Newton's diagram’ to find the series expansions of an algebraic function q(x) in the neighbourhood of a point x0 . In this paper it is shown how, for a linear, time-invariant, multi-variable feedback system, this method can be used to find : (i) the asymptotic behaviour of the characteristic frequency loci (multivariable root loci) ; (ii) the angles of departure of the characteristic frequency loci from the open-loop poles ; and (iii) the angles of approach of the characteristic frequency loci to the finite zeros of such a system.