Transfer function identification

clear all;
close all;
clc;
warning off;

global ti ui yi Ks h1s h2s

load Ident13.mat

ti=simout(:,1)';
ui=simout(:,3)'-4.1;
yi=simout(:,2)'-3.7;

%plot(ti, ui, ti, yi);

Ks =0.1792;
h1s =1;
h2s =0.4941;

X0=[Ks, h1s, h2s];

OPTIONS=optimset('MaxIter',100,'Display','iter','MaxFunEval',1000);
X=fminsearch('Ident_krit',X0,OPTIONS);

Ks =X(1);
h1s =X(2);
h2s =X(3);

F1=tf(Ks, [h1s h2s 1])
ysim=step(F1,ti);
plot(ti,yi,ti,ysim)

%this is separate function Ident_krit
function J=Ident_krit(a);

global Ks h1s h2s ti

Ks = a(1);
h1s = a(2);
h2s = a(3);

sim('Ident_sim',ti(end));

J=Jsim