bodedm

Programmatically generate the bode plot showing the margins as data cursors at once

With just the transfer function, "bodedm" allows you to plot the margins as data cursors:
Example:
clc, clear, close all
T = 1;
k = 5*100*50;
z = [];
p = [0 -30 -50];
Gs = zpk(z,p,k)
bodedm(Gs); grid