This paper shows that many robust control problems can be formulated as con
strained optimization problems and can be tackled by using randomized algor
ithms. Two different approaches in searching reliable solutions to robustne
ss analysis problems under constraints are proposed, and the minimum comput
ational efforts for achieving certain reliability and accuracy are investig
ated and bounds for sample size are derived. Moreover, the existing order s
tatistics distribution theory is extended to the general case in which the
distribution of population is not assumed to be continuous and the order st
atistics is associated with certain constraints.