%% Structured vs. unstructured uncertainty 
% Example 8.5 from Skogestad

M = [2 2; -1 -1]

[U,S,V] = svd(M)

V1 = V(:,1)
U1 = U(:,1)

sigma1 = S(1,1)

1/sigma1

%% Unstructured uncertainty (Delta matrix full)
Delta = 1/sigma1*V1*U1'
det(eye(2,2)-M*Delta)

hinfM = sigma1

%% Structured uncertainty (Delta matrix diagonal)
Delta = 1/3*diag([1,-1])   
det(eye(2,2)-M*Delta)

muM = 3