the right half-plane, then σ
0 will be positive, and the oscillations will grow exponentially (until
some nonlinearity limits their growth), as shown in Fig. 10.35(b). Finally, if the poles are on the
jω axis, then σ
0 will be zero and the oscillations will be sustained, as shown in Fig. 10.35(c).
Although the discussion above is in terms of complex-conjugate poles, it can be shown
that the existence of any right-half-plane poles results in instability.