Why do I get the error?

This is my code

t=0:.1:5;
u(1:25)=.1;
u(26:51)=-.1;
plot(t,u);
[to,yo]=sim('hw3',5,[],[t',u']);

%Finding u_final and cost
l_b=ones(51,1)*(-50);
u_b=ones(51,1)*50;
options=optimset('Display','iter','PlotFcns','optimplotx');
[u_final,cost]=fmincon('find_cost',u,[],[],[],[],l_b,u_b,'find_constraint',options);
[t_f,x_f,y_f]=sim('hw3',5,[],[t' u_final']);
figure(3);
subplot(t_f,y_f(:,1));
grid;
xlabel('Time');
ylabel('Position');

figure(4);
subplot(t_f,y_f(:,2));
grid;
xlabel('Time');
ylabel('Velocity');

figure(5);
subplot(t_f,y_f(:,3));
grid;
xlabel('Time');
ylabel('Acceleration');

figure(6);
subplot(t_f,y_f(:,4));
grid;
xlabel('Time');
ylabel('Jerk');

figure(7);
subplot(t_f,y_f(:,5));
grid;
xlabel('Time');
ylabel('Jounce');

Every time i run the code it says Vectors must be of same length.

u and t should be of same size. Please help

[Image Analyst]

I can't run it. Says

To use 'sim', at least one of the following products must be licensed, installed, and enabled:
  Model Predictive Control Toolbox
  Neural Network Toolbox
  Simulink
  System Identification Toolbox
Error in test5 (line 5)
[to,yo]=sim('hw3',5,[],[t',u']);

You forgot to list what products are needed on the right of this page. Please do so.

So, exactly what are your u and t, and why aren't they the same size?

[KSSV]

Which line you get error? It has some input file hw3

[Aishwarya Bangalore Kumar]

'hw3' is a simulink model. sim is a form of communication between matlab and simulink. I m getting the error in line 4

plot(t,u)

They are time and state of a function respectively

[KSSV]

t=0:.1:5;
u(1:25)=.1;
u(26:51)=-.1;
plot(t,u);

The above is working fine....t and u are vectors of size 1X51.

[Aishwarya Bangalore Kumar]

I am still getting the same error

[Aishwarya Bangalore Kumar]

I understood sir thank you

Answer 1

[KSSV]

Use this:

t=0:.1:5;
u = zeros(size(t)) ;
u(1:round(length(t)/2))=.1;
u(round(length(t)/2)+1:end)=-.1;

plot(t,u);