Empirical Methods for Determining the Stability or Instability of Certain Transfer Functions

We present some empirical methods for determining whether a linear autonomous dynamical system which has a known analytic transfer function is stable or unstable. These methods are based on the Poisson Integral representation for H` mappings. Approximations of these integrals are often easily implemented by standard numerical packages, such as MATLAB, and thus present practical procedures for determining whether a given transfer function does or does not belong to H`. Q