Abstract:
In this paper the problem of measuring the robustness of stability
for a perturbed continuous time nonlinear system at a singular fixed
point is studied. Various stability radii are introduced and their
values for the nonlinear system and its linearization are compared.
It is shown that they generically coincide. This result may also be
used to show generic continuity of linear real stability radii.
Some examples are presented showing that it is sometimes necessary
to consider the nonlinear system directly, and not simply to rely on
the information provided by the linearization.