Why these two codes produce different graphs? How can I make the second graph be like the first?

Why these two codes produce different graphs? How can I make the second graph be like the first?

1st:

    t=0:0.3:10;
step(c2d(tf(1,[1 1]),0.3),t);

2nd:

t=0:0.3:10;
[y,t]=step(c2d(tf(1,[1 1]),0.3),t);
plot(t,y)

[sadel]

Any idea?

Answer 1

[Arnaud Miege]

Fangjun's correct. To get the same plot, use stairs:

stairs(t,y)

HTH,

Arnaud

Answer 2

[Fangjun Jiang]

The results are same if you see it like this.

figure;
plot(t,y,'+');

I think the reason is: you are calculating the step response of a discrete system so the plot shown in your first step() line shows the results as the value at every discrete time step. The plot shown in your plot() line is interpreted by the plot() command.

See also

step(tf(1,[1 1]),t)