Plotting Step Responses with For Loops

Hi, I have a problem with the plot command in regards to plotting step responses in for loops. I've searched everywhere and cannot find what I'm looking for. I am hoping someone can help me. Here's my problem:

I need to plot a simple step response over a series of different time constants. It's a first order system with time constant ranging from 35 over multiples of 5 to 60, and it begins at 25 and ends at 100 (it's a temperature problem).

Here's my code:

>> for tau=35:5:60,
sys=tf([75],[tau 1]);
y=25+step(sys);
plot(y)
hold on
end

And with that, all I get is one curve using the last tau of 60. And that's the value MATLAB stores even though I told it to keep 35-->60. If I use just "step(sys)", I get all my curves. I think it has something to do with the plot command. Any help is appreciated--thank you in advance!!

Answer 1

[Rick Rosson]

figure;
axes;
hold on;
for tau = 35:5:60
    sys = tf([75],[tau 1]);
    [y,t] = step(sys);
    plot(t,25+y);
end

[N/A]

Yes! Thank you so much! I wonder why the loop didn't hold for my code? Because if I would just directly use

step(sys)
hold on
end

...everything works (except the 25 increase at the beginning). Either way, now it works, so thank you!