338 Martin Fischer
ak(t) = A~ak(O)
If we express the complex eigenvalues A k as
A k = IAkl exp(iffi k ) = exp(-th)exp«i27t)/T k )
we obtain for each POP a characteristic e-folding (decay) time
and an oscillation period T k
Thus, the POP model describes a damped oscillation in the complex plane.
(B7)
(B8)
(B9)
(BlO)