how to use mussv with negative frequency?

I want to compute mussv values with negative frequency. How I can implement this ? This is required because my state space model is complex.

Answer 1

[Paul]

mussv appears to run w/o error for a complex-valued state space model and does extend its analysis to negative frequencies.

Alternatively, the ss model can be converted to an frd model and then call mussv on the frd model.

rng(100)
sys = rss(2,2,2);
sys.a = sys.a + 1j*rand(2);  % make the model have a complex system matrix
bounds = mussv(sys,[1,0;1,0]);

Computing bounds... Points completed: 84/84
Computing peak...  Percent completed: 100/100
Computing peak...  Percent completed: 100/100

figure
plot(bounds.Frequency,squeeze(bounds.ResponseData(1,1,:)),'-x','DisplayName','Upper Bound');
hold on;
plot(bounds.Frequency,0*squeeze(bounds.ResponseData(1,2,:)),'-o','DisplayName','Lower Bound');
legend
xlim([-1000,1000])