MATLAB: Error – Brace indexing is not supported for variables of this type.

Question

Hi all,

I'm trying to find a matrix C that does not contain certain rows a{count4} where count4 = 1:N (N is an input). To do this I'm using the function setdiff but it does not seem to work within the for loop, but works outside of the loop. Here is my code:

function [] = Lyapunov(l,k,n,N)
for count = 1:n
    e(count) = (1/(2*count*(count+1)))^(1/2);
end
for count2 = 1:n
    if count2 == 1
        w{count2} = [2*e(1) zeros(1,n-count2)];
    else
        w{count2} = [e(1:(count2-1)) (count2+1)*e(count2) zeros(1,n-count2)];
    end
end
A = [];
x = randi([-1 1],1,N);
y = randi([-1 1],1,N);
for count3 = 1:N
    a{count3} = [x(count3) y(count3)];
    A = [A;a{count3}];
end
C = setdiff(A,a{1},'rows') %this works
for count4 = 1:N
    C = setdiff(A,a{count4},'rows'); %this does not work
    c = size(C,1);
    a = size(A,1);
    if c<a-1
        A(count4,:) = [];
    end
end
A
size(A,1)
end

and here is the error message:

Brace indexing is not supported for variables of this type.
Error in Lyapunov (line 21)
    C = setdiff(A,a{count4},'rows');

I would appreciate any help you all can give me, thank you in advance 🙂

Answer 1

    a = size(A,1);

That replaces the cell a with a numeric scalar.