Trouble Solving for Variables Using 3 Separate Numbers

Assignment is "write a MATLAB script file (Lab07p2.m) that plots the tensions for Theta=5,10,...85 deg, LAC=6 ft, LAB=3,6,9 ft, and W=2000 lb.

So heres my code: it works perfectly with one number in for LAB but when I plug in 3 it doesn't. Not sure how to fix this and/or if there is a simple way to do so.

CODE::

        lab       = (3 6 9);        {PROBLEM AREA}                     %ft
        lac       = 6;                                                 %ft
        W         = 2000;                                              %lbs
        theta     = (5:5:85);                                          %degrees
        phi       = atand(lab.*sind(theta) ./ (lac-lab.*cosd(theta))); %degrees
        Lbc       = lab.*sind(theta) ./ sind(phi);                     %ft
        Tab       = (W.*cosd(phi)) ./ ((sind(theta)+ cosd(theta)).*(sind(phi))); 
        Tbc       = (Tab.*cosd(theta)) ./ (cosd(phi));
        T         = max(Tab, Tbc);
        plot(Tab, Tbc);

Any advice/fixes will be greatly appreciated!! Thank YOU :)

Answer 1

[Stephan]

Hi,

vectors are defined by square brackets. Then additionally use the colon operator ':' since your result gets a matrix:

lab = [1 2 4];      %  {PROBLEM AREA}                     %ft
lac       = 6;                                                 %ft
W         = 2000;                                              %lbs
theta     = (5:5:85);                                          %degrees
phi       = atand(lab(:).*sind(theta) ./ (lac-lab(:).*cosd(theta))); %degrees
Lbc       = lab(:).*sind(theta) ./ sind(phi);                     %ft
Tab       = (W.*cosd(phi)) ./ ((sind(theta)+ cosd(theta)).*(sind(phi))); 
Tbc       = (Tab.*cosd(theta)) ./ (cosd(phi));
T         = max(Tab, Tbc);
plot(Tab', Tbc');

Best regards

Stephan