MATLAB - 伯德图

MATLAB - Bode plot

如何绘制以下传递函数?

A = 5;
num = [A];
den = [];
fun = tf(num, den);
bode(fun);

如何输入底线?

s= tf([1 0],1) % s contains the tf object with `s` transfer function
system= 5/(1+s/w1)/(1+s/w2)/(1+s/w3) % this works due to the operator overloading
bode(system)