This is the main property of Simulink. If you write a function yourself, you need to define the size of output at the very beginning of the function. The error comes from that you define G empty, in which Simulink will think that its size is fixed and won't change during the simulation. Therefore, you need to preallocate some space for your output G. Consider the following approach:
function G = my_fcn(X)
G = zeros(11,1);
nule = zerocros(X);
k = size(nule);
n = 1;
i = 0;
for i=1:k(1,1)
if i + 10 > k(1,1)
break
end
Y = nule(i:i+10);
if Y(11) > 10
G(:,n) = Y - Y(1);
G(:,n) = G(:,n)./G(11,n);
G(1,n) = nule(i);
G(11,n) = Y(11);
n = n + 1;
end
end
At the very beginning, I told Simulink that output G is going to be a column vector which has 11 rows. If you try to create new row during the simulation, it will throw an error, therefore always be careful to stay within predefined sizes.
