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Compute poles of dynamic system
pole(sys)
pole(sys) computes the poles p of the SISO or MIMO dynamic system model sys.
If sys has internal delays, poles are obtained by first setting all internal delays to zero (creating a zero-order Padé approximation) so that the system has a finite number of zeros. For some systems, setting delays to 0 creates singular algebraic loops, which result in either improper or ill-defined, zero-delay approximations. For these systems, pole returns an error. This error does not imply a problem with the model sys itself.
Multiple poles are numerically sensitive and cannot be computed to high accuracy. A pole λ with multiplicity m typically gives rise to a cluster of computed poles distributed on a circle with center λ and radius of order
$$\rho \approx {\epsilon}^{1/m}$$
where ε is the relative machine precision (eps).