ANALYTIC CRITERIA FOR THE STABILITY OF LINEAR SYSTEMS WITH TIME DELAY

An analytic criterion for determining the stability of linear differential delay systems is presented. The charac-teristic function of such a system is a quasipolynomial, i.e. a polynomial multiplied by the exponential function plus another polynomial. Using concepts of the theory of functions one can show that by evaluating the path integral over the characteristic function along the positive part of the imaginary axis the stability of the system can be determine