%  use 'help' command to understand the functions and their usage
%  examples: 
%   1)   help tf
%   2)   help zpk
%   3)   help residue

clear
format compact

s = tf('s');
fs = (8*s^2+120*s+400)/(2*s^4+20*s^3+70*s^2+100*s+48);

fs_zpk = zpk(fs)
fs_zpk.p{1}
fs_zpk.z{1}
fs.num{1}
fs.den{1}

% [R,P,K] = residue(B,A)
[R,P,K] = residue(fs.num{1},fs.den{1})


[B,A] = residue(R,P,K)
my_tf = tf(B,A)

IL = 100*s^2/((s^2+(120*pi)^2)*(s^2+1500*s+1e6));
[R,P,K] = residue(IL.num{1},IL.den{1})