Error with FOR loop and SQRT: In an assignment A(I) = B, the number of elements in B and I must be the same.

Would someone be able to help explain why I am getting the error in the FOR loop with the SQRT function and how to fix it. I am getting the error in the second to third calculation of the loop for the equation "c" This is for an urgent assignment due ASAP. Thanks for the review!

My Code:

%Define theta Vector
for n=1:N
    theta(n)=n*pi/(N+1);
end
theta=theta'

%Define y-axis
for i=1:N
  y(i)=-(b/2)*cos(theta(i));
end
  y=y'

% Wing chord vartion type ChordType, 1-elliptical, 2-rectangular, 3-tapered, 4-other
if ChordType==1
    for i=1:N
        c(i)=c*sqrt(1-(y(i)/(b/2))^2)
    end
elseif ChordType==2
    c(1:N)=c
end
c=c'

Output for when N=10, using a c0 =10*pi/4=7.85398 and b=1 with AR=10

y =

     -3.7679
     -3.3036
     -2.5716
     -1.6313
     -0.5589
      0.5589
      1.6313
      2.5716
      3.3036
      3.7679

c =

      0.2817    0.1523

In Red Color output ERROR:

In an assignment  A(I) = B, the number of elements in B and I must be the same.

Error in PA1do_geom3 (line 43)
        c(i)=c*sqrt(1-(y(i)/(b/2))^2)

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency

Answer 1

[Mischa Kim]

Michael, in

 for i=1:N
        c(i)=c*sqrt(1-(y(i)/(b/2))^2)
 end

c is a vector of varying size (growing), which you are trying to assign to a scalar, c(i). I assume you are trying to do something like

 for i = 2:N
     c(i) = c(i-1)*sqrt(1-(y(i)/(b/2))^2)
 end

Note, that the indexing in MATLAB starts at 1 not 0. So your initial value c0 would be c(1).

Also, I recommend not using i or j as variables because they are also used as the imaginary unit in MATLAB.