# simulate State Space system with lsim

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Anthony Sirico on 4 Feb 2021
Answered: Star Strider on 4 Feb 2021
A = [0 1 0 0; 0 0 1 0; 0 0 0 1; -2 -5 -7 -2];
B = [0; 0; 0; 1];
C = [1 3 0 0];
D = 0;
t = 10;
sys = ss(A,B,C,D);
x0 = [1 1 1 1];
u = exp(-0.3*t)*sin(t);
lsim(sys, u, t)
grid
I was given this ss system, but it keeps returning:
Error using DynamicSystem/lsim (line 97)
When simulating the response to a specific input signal, the input data U must be a matrix of numeric values with at least two
rows (samples) and without any NaN or Inf.
Error in HW2_2b (line 15)
lsim(sys, u, t)
Any ideas?

Star Strider on 4 Feb 2021
For a SISO system, ‘t’ needs to be a vector:
t = linspace(0,10);
the full code being:
A = [0 1 0 0; 0 0 1 0; 0 0 0 1; -2 -5 -7 -2];
B = [0; 0; 0; 1];
C = [1 3 0 0];
D = 0;
t = linspace(0,10);
sys = ss(A,B,C,D);
x0 = [1 1 1 1];
u = exp(-0.3*t).*sin(2*pi*t);
lsim(sys, u, t)
grid
Create ‘t’ to be whatever you want.

R2020b

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