i dont understand the error here, where do i put the parantheses??

% The command below loads the following variables:
% y: vector of output data
% t: vector of corresponding times
% yss: steady-state output
load variables.mat
S=stepinfo(y,t,yss)
% Estimate the parameters of the underdamped, second-order system:


zeta = (-log(S.Overshoot/100))/((pi^2 +(log(S.Overshoot/100)) ^2) ^0.5)  % damping ratio 
wn = pi/((S.PeakTime)(1-(zeta)^2)^ 0.5)  % natural frequency (in rad/sec)

K = yss(wn)^2 % gain

Answer 1

[the cyclist]

It looks like on this line of your code:

wn = pi/((S.PeakTime)(1-(zeta)^2)^ 0.5)

you are assuming that MATLAB will understand that

(a)(b)

means you should mutliply a and b, but that is not valid MATLAB syntax. Perhaps you meant

wn = pi/((S.PeakTime).*(1-(zeta)^2)^ 0.5)

?

[yasmine]

Yep it worked thank you very much!