Please optimise the parameter P with respect to the performance criterion IAE using the steepest descent minimisation process in this Matlab script.

clear all close all clc %setup the given TF: num=[22.5]; den=[4 3.6 36]; sys=tf(num,den);

%sampling time: Ts = 1.0881; % min

% add kp parameter to P controller: Kp = 100; Ki = 100; Kd = 100; C = pid(Kp,Ki,Kd); % close loop with feedback: sys_cl = feedback(C*sys,1);

%Zero hold to discretize the signal: Ghp = c2d(sys_cl,Ts,'zoh')

%step response plot of the proportional controller: step(Ghp) grid