clear; close all
s=tf('s');

Gp=15/(s*(s + 1.2)*(s + 5));
Gplc=feedback(Gp,1)
figure; step(Gplc)

zpk(Gplc)

%                    15
% Gpr=  --------------------------------
%       (s+5.607) (s^2 + 0.593s + 2.675)

[ceros,polos,K]=zpkdata(Gplc,'v');
den=(s - polos(2))*(s - polos(3));
num=K;
Gpa=(num/den);
Gpa=(1/dcgain(Gpa))*Gpa
zpk(Gpa)

figure
step(Gplc,Gpa)
legend('Gp real','Gp aprox')