Why does the array only work once?

Hey guys,

I'm having trouble with the code in trying to find the angle phi. The calculation for AD uses Theta as I intended, but when calculating Phi, I only get one answer instead of multiple. This makes the rest of my code incorrect. Any suggestions?

% Givens
AB = 150;
BD = 200;
Theta = 20:120;
Mb = 2.5;

%Solutions

AD = sqrt(BD^2 + AB^2-2*BD*AB*cosd(Theta));

%Finding angle Phi of force P

    
Phi = asind(AB*sind(Theta)/AD);


%Finding force P

P = Mb/(BD*sind(90 - Phi));

%Finding Ma

Ma = P * AD;

Answer 1

[Star Strider]

Use element-wise division:

Phi = asind(AB*sind(Theta)./AD);
                          ↑ ← HERE

and:

P = Mb./(BD*sind(90 - Phi));
      ↑ ← HERE

and element-wide multiplication:

Ma = P .* AD;
       ↑ ← HERE

and the calculations do what you want them to do.

[Marcos Dominguez]

Thank you! This fixed my code, just right!

[Star Strider]

As always, my pleasure!

Answer 2

[Alan Stevens]

You need element by element multiplication and division:

% Givens
AB = 150;
BD = 200;
Theta = 20:120;
Mb = 2.5;

%Solutions

AD = sqrt(BD^2 + AB^2-2*BD*AB*cosd(Theta));

%Finding angle Phi of force P

    
Phi = asind(AB*sind(Theta)./AD);  %%%%%  ./ not just /


%Finding force P

P = Mb./(BD*sind(90 - Phi));    %%%%%  ./ not just /

%Finding Ma

Ma = P.* AD;   %%%%%  .* not just *

[Marcos Dominguez]

Thank you sir. This fixed my code.

Answer 3

[Sulaymon Eshkabilov]

Hi,

You have overlooked a few dot operations. Here is the corrected part of your code:

%Finding angle Phi of force P    
Phi = asind(AB*sind(Theta)./AD);
%Finding force P
P = Mb./(BD*sind(90 - Phi));
%Finding Ma
Ma = P.*AD;

[Marcos Dominguez]

Thank you! It worked!