Mass spring system - state space - matlab

A = [0,0,1,0;0,0,0,1;-4,2,-2,1;2,-4,1,-2];
B = [0;0;10;0];
C = [0,1,0,0];
D = 0;

G = ss(A,B,C,D);
zpk(G)
t = [0:0.1:10]';
y = step(G,t);
plot(t,y)

[z,p,k] = ss2zp(A,B,C,D)

Source: http://bisonacademy.com/