how can i create nonlinear uncertainty?

I want to define a diagonal matrix that each element of them is an nonlinear uncertainty with value bound of for example 0.4 with mu toolbox or defined in another way ?

[Walter Roberson]

I don't think I understand the question.

Is "mu toolbox" Mu Sythesis for robust controllers? https://www.mathworks.com/help/robust/mu-synthesis.html ?

[elahe mastani]

yes it is

[elahe mastani]

i want to define delta= diag [delta1(); : : : ;deltam()] where delta(.) is a nonlinear operator. We assume that delta(0) = 0 is the unique equilibrium point and define the infinity norm of delta()