It’s likely not an error, simply a suggestion that preallocating for speed would be advisable. (A preallocated loop generally requires about 20% less time compared to not preallocating.) It is most likely to appear with respect to a loop that stores values. The only one that I can see where that would work is:
for i=1:10
fval(i) = func(xval(i));
end
because it has a fixed number of iterations.
It could also work in the while loop because you are storing ‘z’, however unless you know about how many iterations that loop would require, preallocating would simply be a guess. One way to do that in the while loop would be to preallocate with perhaps:
and when the loop finishes, use the rmmissing function to remove any remaining NaN values. This assumes that the calculation of ‘x’ never produces a NaN value.
The preallocation statements would be placed just before their respective loops.
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