Error using ==> zeros Maximum variable size allowed by the program is exceeded.

I keep getting the error below, the program which creates a (1 x 21) matrix. I have 8 Gb of memory on my pc surely this small matrix doesn't take up this much memory?

??? Error using ==> zeros Maximum variable size allowed by the program is exceeded.

Error in ==> Task1_2_38 at 29 diff = zeros(1:n);

y = -b/2:.1:b/2;
D = .05;
lift_dist = d*v*sqrt(1-((2*y)/b).^2); %lift distribution in this case elliptical
n = length(lift_dist);
for ind = 1:n
circ_dist = lift_dist./(d*v);  % circulation distribution
%display(circ_dist)
end  
%figure(1)
  %plot(y,circ_dist)%plot circulation distribution vs the wing span (y)
  %display(y)
%number of sectiond for the airfoill
dy = b/(n-1);
%vector initialization
induced_angle = zeros(1,n);
%Calculate the constants for the induced angle equation:
diff = zeros(1:n);
while (norm(diff) > 1e-5)

Answer 1

[Walter Roberson]

http://www.mathworks.com/help/techdoc/ref/zeros.html

B = zeros(m,n,p,...) or B = zeros([m n p ...]) returns an m-by-n-by-p-by-... array of zeros.

Now, 1:n is the same as the vector [1 2 3 4 5 6 ... n]

so

zeros(1:n)

is the same as

zeros([1,2,3,4,...n])

which would request factorial(n) array locations. If your n is 21, that would be 51090942171709440000 array locations, which is between 2^65 and 2^66 array locations, and thus would require between 2^68 and 2^69 bytes of storage.

[James]

I see, but then why in the line "induced_angle = zeros(1,n);" do I not see the same problem?

[Jan]

@James: Because "zeros(1, n)" creates a [1 x n] vector.

Did you get the point already? "zeros(1:n)" is very different from "zeros(1, n)".

[James]

Oh, crap I am an idiot, got it thanks.

Answer 2

[James]

Wow, I feel like an idiot, this is why I should have just went to bed last night.

[Walter Roberson]

Don't feel too bad. See Matt Fig's answer in

http://www.mathworks.com/matlabcentral/answers/1759-dumb-mistakes-we-make-with-matlab