  A dual formulation for the problem of determining absolute performance
limitations on overshoot, undershoot, maximum amplitude and fluctuation
minimization for continuous-time feedback systems is constructed. Determining,
for example, the minimum possible overshoot attainable by all possible
stabilizing controllers is an optimization task that cannot be expressed as a
minimum-norm problem. It is this fact, coupled with the continuous-time rather
than discrete-time formulation, that makes these problems challenging. We
extend previous results to include more general reference functions, and derive
new results (in continuous time) on the influence of pole/zero locations on
achievable time-domain performance.
