Why is my Plot Blank?

Hi, my code returns a blank plot and I dont know why

Code:

beta1 = 0.1

theta = [0: 0.1: 90];

      function dyds = motorbike(betas)
          for theta = [0: 0.1: 90]
              a = 3/(8*betas);
              b = sqrt(8*(sind(theta)).^2 + 1);
              c = sind(theta)*(cosd(theta)).^3;
              dyds = a*(b/c);
          end
          %dyds = (3/(8*betas))*sqrt((8*sin(theta).^2)+1)/sin(theta)*cos(theta).^3;
      end
  figure
  plot(theta, motorbike(beta1))

Answer 1

[Roger Stafford]

You need to index dyds so that it contains a value for each value of ‘theta’:

dyds = zeros(1,length(theta));
for k = 1:length(theta)
 ...
 b = sqrt(8*(sind(theta(k))).^2 + 1);
 c = sind(theta(k))*(cosd(theta(k))).^3;
 dyds(k) = a*(b/c);
end

Answer 2

[Thorsten]

You don't need the for loop, you can work on the vector beta. You just have to replace * and / with .* and ./ (you already use .^)

 betas = 0.1

 theta = [0: 0.1: 90];
 a = 3/(8*betas);
 b = sqrt(8*(sind(theta)).^2 + 1);
 c = sind(theta).*(cosd(theta)).^3;
 dyds = a.*(b./c);