Why does matlab plot the unit step like a straight line?

Hello, I want to pot only the unit step in matlab with this code:

s=tf('s')
sys=1/s

I expectet the step response like this:

But i get a plot in matlab like this:

Why do I get a step response like the second picture. Should a step input it not look like my first picture? Thanks

Answer 1

[Sam Chak]

Hi @Mark S

System 1:

s    = tf('s');
sys1 = 1/s;             % integrator system
step(sys1)

System 2:

sys2 = zpk([], [], 1)   % just a static gain

sys2 =
 
  1
 
Static gain.

step(sys2)

Answer 2

[Dyuman Joshi]

Because that's what the step response of the transfer function you mentioned looks like.

You might be looking for heaviside

syms x
fplot(heaviside(x), [-5, 5],"LineWidth",1.5)
ylim([0 1.5])