function Ai = ex_estab_c_OP06a_ex3(rho)
%function Ai = ex_estab_c_OP06a_ex3(rho)
% Continuous-time uncertain system used for robust stability evaluation purposes. This systems was
% used in (Oliveira & Peres, SCL 2006), Example 3.

if nargin == 0
    rho = 2.2237;
end

A0 = [-2.4 -0.6  -1.7  3.1;
    0.7  -2.1  -2.6 -3.6;
    0.5   2.4  -5   -1.6;
    -0.6   2.9  -2   -0.6];

A1 = [1.1 -0.6 -0.3 -0.1;
    -0.8 0.2 -1.1 2.8;
    -1.9 0.8 -1.1 2;
    -2.4 -3.1 -3.7 -0.1];

A2 = [0.9 3.4 1.7 1.5;
    -3.4 -1.4 1.3 1.4;
    1.1 2 -1.5 -3.4;
    -0.4 0.5 2.3 1.5];

A3 = [-1 -1.4 -0.7 -0.7;
    2.1 0.6 -0.1 -2.1;
    0.4 -1.4 1.3 0.7;
    1.5 0.9 0.4 -0.5];

A11 = A0 + rho*A1;
A12 = A0 + rho*A2;
A13 = A0 + rho*A3;
Ai = [A11 A12 A13];
