*Matrix dimensions must agree error*

I am relatively new to Matlab and is working on a problem but keep getting this error. Please help! I attached the matlab file, but is also posting a screenshot.

Answer 1

[Alan Stevens]

Look up .* (i.e. dot*), ./ and .^ for element by element actions. Replace the later part of your code by

x=linspace(0.5,1);
Vx=V1*cos(x);
Vy=V1*sin(x);

%===========
%Calculations
%===========
y1=(L4./(V1*cos(x)));  % ./ not just /
y2=((-g/2)*(L4./(V1*cos(x)).^2)+V1*sin(x).*(L4./(V1*cos(x)))+L3);  % ./, .^ and .*  y2?
y3=Vb*(L4./(V1*cos(x)))+L1;  % ./


plot(x,y1,x,y2,x,y3),grid
xlabel('x'),ylabel('y')
legend('y1','y2','y3')

Answer 2

[Mohamad]

Hi , I made the required corrections in the code , now it is working , I also plot y1 and y3 .

%==============================
% Computer based assigment - dynamics
%==============================
% Question 1
%Given
L1=14;
L2=25;
L3=2;
L4=100;
Vb=6;
V1=40;
g=9.81;
x=linspace(0.5,1);
Vx=V1*cos(x);
Vy=V1*sin(x);
%===========
%Calculations
%===========
y1=(L4./(V1*cos(x)));
y3=(-0.5*g*(L4./(Vx).^2)+Vy.*(L4./(Vx))+L3);
y3=Vb*(L4./(Vx))+L1;
subplot(211) ; plot(x,y1) ; grid
subplot(212) ; plot(x,y3) ; grid

[Alan Stevens]

Note that you have two expressions for y3.