function Ai = ex_estab_d_OP06a_ex4()
%function Ai = ex_estab_d_OP06a_ex4()
% Discrete-time uncertain system used for robust stability evaluation purposes. This systems was
% used in (Oliveira & Peres, SCL 2006), Example 4.

A0 =[ -0.7 0.7 0
    -0.1 -0.3 -0.3
    -0.1 0.3 0.3];

A1 = [-0.7 -0.3 0.4
    0.7 0.7 -0.5
    -1.5 0.1 0.7];

A2 = [-1 -1 0.6
    0.4 0.9 0.1
    -2.7 -1.2 -0.6];

Ai = [];
ro=0.38409;
for ro1=-ro:2*ro:ro
    for ro2=-ro:2*ro:ro
        Ai = [Ai (A0 + ro1*A1 + ro2*A2)];
    end
end
