The worst-case gain measure is the maximum achievable system gain over all uncertain elements whose normalized size is bounded by 1.
On the graph, this is the vertical coordinate of the performance degradation curve as it crosses the vertical line drawn at the uncertainty bound = 1.
Each measure captures a single scalar attribute of the system
performance degradation curve. Mathematically, they are
independent quantities, answering subtlely different questions. Consequently,
for two uncertain systems,
it is possible that the
is larger than the
is smaller than the
Nevertheless, they are useful metrics for concise description of the
robustness of a system (
due to various uncertain elements.