%%% Bug Report
close all
clear

csi = 0.01;
wn1 = 100;
wn2 = 10000;

s = tf('s')

G1 = 100/(s^2*(s^2+2*csi*wn1 + wn1^2))


w = [1:1e-3:1e4];
bode(G1,w);

figure
margin(G1)