Error using reshape-I'm not sure whats causing the issue

I am currently working on this project where I have to (1) convert the differential equation of motion to the state-space matrix equations using the linear system theory. (2) Plot the step response of the open-loop system using Matlab. Evaluate the dynamic response of

the system. (3) Plot the step response of the design of your close-loop system with the provided controller.

Ive gotten as far as step 2, and Im trying to plot it but no matter what i do i keep getting the same error:

Error using reshape

Number of elements must not change. Use [] as one of the size

inputs to automatically calculate the appropriate size for that

dimension.

Error in symengine>@(t)reshape([0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,(sqrt(1.0e+1).*sin(sqrt(1.0e+1).*t.*(7.0./2.0e+1)))./7.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,cos(sqrt(1.0e+1).*t.*(7.0./2.0e+1)).*(-2.0e+1./4.9e+1)+2.0e+1./4.9e+1],[5,4])

Error in (line 27)

plot(t,zeta(t))

I dont understand what this means, the plot portion of the code was provided for the project, what would be causing this?

clear all; clc;
M = 2; %kg
m = 0.5; %kg
L = 0.5; %m

% xmatrix = [x theta; xdot thetadot]

MM=[M+m,m*L;m*L,m*L^2]; 
K=[0,0;0,m*9.8*L]; 

am = (inv(-M)).*K;

OO = zeros(size(eye(2)));
I = eye(2);
A = [OO I ; am OO];
B =[0; 0; 0; 0;inv(M)];
D = [0 1 0 0];

syms G s  
Gs=D*(inv(s.*eye(4)-A)).*B; 
zeta=matlabFunction(ilaplace(Gs/s)); 


t=1:0.01:3; 
plot(t,zeta(t))

% K=[0.2349 15.53 0.3171 -0.5668]; 
% Gcs=simplify(D*inv(s*eye(4)-A+B*K)*B)

Answer 1

[KSSV]

Your zeta is a function handle which gives you 4x4 matrix. You cannot plot it using plot.

Check:

t=1:0.01:3; 
for i = 1:length(t)
    zeta(t(i))
end

[Bryanna Seward]

Thank you so much! This fixed the issue completely, and i was able to move on! Again thank you so much!

Answer 2

[Walter Roberson]

@(t)reshape([0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,(sqrt(1.0e+1).*sin(sqrt(1.0e+1).*t.*(7.0./2.0e+1)))./7.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,cos(sqrt(1.0e+1).*t.*(7.0./2.0e+1)).*(-2.0e+1./4.9e+1)+2.0e+1./4.9e+1],[5,4])

in order for that reshape() to work, then t would have to be a scalar.

t=1:0.01:3; 

but it is not a scalar. When you matlabFunction and pass in a vector variable, the t in the generated function is going to expand to the complete variable content.

In particular, matlabFunction is not going to automatically create code that does

@(t)reshape([zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),(sqrt(1.0e+1).*sin(sqrt(1.0e+1).*reshape(t,1,1,[]).*(7.0./2.0e+1)))./7.0,zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),zeros(1,1,numel(t)),cos(sqrt(1.0e+1).*reshape(t,1,1,[]).*(7.0./2.0e+1)).*(-2.0e+1./4.9e+1)+2.0e+1./4.9e+1],5,4,[])

to create a 5 x 4 x length(t) array of output.

[Walter Roberson]

M = 2; %kg
m = 0.5; %kg
L = 0.5; %m
% xmatrix = [x theta; xdot thetadot]
MM=[M+m,m*L;m*L,m*L^2]; 
K=[0,0;0,m*9.8*L]; 
am = (inv(-M)).*K;
OO = zeros(size(eye(2)));
I = eye(2);
A = [OO I ; am OO];
B =[0; 0; 0; 0;inv(M)];
D = [0 1 0 0];
syms G s  
Gs=D*(inv(s.*eye(4)-A)).*B

Gs = 

Z = ilaplace(Gs/s)

Z = 

Your Gs is an array, so your ilaplace() is going to be an array.

Does it make sense to plot() an array?