how to store your outputs of your step response?

A = [0 0 1 0;0 0 0 1;-24 9 -3 0;4.5 -4.5 0 0]; B=[0 0;0 0;12 4;0 3.5]; C = [0 0 1 0;0 0 -3 0]; D = [0 0;0 0];

step(A,B,C,D)

how can i store the outputs of this step response so i can plot them together on a separate plot?

Answer 1

[Azzi Abdelmalek]

A = [0 0 1 0;0 0 0 1;-24 9 -3 0;4.5 -4.5 0 0];
B=[0 0;0 0;12 4;0 3.5];
C = [0 0 1 0;0 0 -3 0];
D = [0 0;0 0];
s=ss(A,B,C,D)
[y,t]=step(s)  % t is time vector
% output1 from input1
y11=y(:,1,1)
% output2 from input1
y21=y(:,2,1)
% output1 from input2
y12=y(:,1,2)
% output2 from input2
y22=y(:,2,2)
subplot(2,1,1)
plotyy(t,y11,t,y12)
title('output 1 & 2 from input 1')
subplot(2,1,2)
plotyy(t,y21,t,y22)
title('output 1 & 2 from input 2')

[Nicholas]

i get an error when doing y12=y(:,1,2)

??? Index exceeds matrix dimensions.

[Azzi Abdelmalek]

Have you copied and paste the code?

[Nicholas]

yes...i did [y,t]=step(A,B,C,D) instead. and also why is my t a 1185 X 8 matrix shouldnt it just be a vector?

[Azzi Abdelmalek]

It's

s=ss(A,B,C,D)
[y,t]=step(s)  % t is time vector

[Nicholas]

o I thought it would work both ways

[Nicholas]

Thank you

[Nicholas]

i think you mixed up your plots

isnt it supposed to be

plotyy(t,y11,t,y21) 
title('output 1 & 2 from input 1')

[Azzi Abdelmalek]

You are right