MATLAB: I don’t understand where the problem is in this system

errorsystem

if true
  % code
switch es
case 1, beta=0.1;  k=2;  x0=[0;0];   w0=0; tmax=20;
case 2, beta=0.01; k=2;  x0=[0;0];   w0=0; tmax=200;
case 3, beta=10;   k=20; x0=[0;0];   w0=0; tmax=10;
case 4, beta=0.1;  k=2;  x0=[0;0.2]; w0=0; tmax=20;
case 5, beta=0.1;  k=2;  x0=[0;0];   w0=4; tmax=10;
case 6, beta=0.01; k=2;  x0=[0;0];   w0=4; tmax=10;
case 7, beta=10;   k=20; x0=[0;0];   w0=4; tmax=10;
case 8, beta=0.1;  k=2;  x0=[0;0.2]; w0=4; tmax=10;
end
m=0.2;
f0=1;
A=[0,-k/m; 1,-k/beta];
B=[1/m,0;0,0];
C=[1,0];
D=0;
sistema=ss(A,B,C,D);
T=0:0.01:tmax;
U=f0*cos(w0*T);
[y,tsim,x]=lsim(sistema,U,T,x0);
end
The error is: Error using DynamicSystem/lsim (line 84) When simulating the response to a specific input signal, the input data U must be a matrix with as many rows as samples in the time vector T, and as many columns as input channels.
Thanks to all!

Best Answer

The message seems to be clear:
 U must be a matrix with as many rows as samples in the time vector T, 
 and as many columns as input channels.
We cannot run your code, e.g. because "k" is undefined. But is looks like U and T have the same number of elements. Then it might be the number of input channels. Did you test this already?
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