I am getting this preallocation warning
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Jan
on 19 Nov 2022
@Vânia Gonçalves: A general hint is to search in the net at first. Asking an internet search engine for "Matlab preallocate" shows useful explanations already.
Answers (2)
Steven Lord
on 19 Nov 2022
This is a Code Analyzer warning not a run-time warning.
If you're not sure what preallocation is, why it can be important, or how to do it see the first example on this documentation page.
Jan
on 19 Nov 2022
Moved: Jan
on 19 Nov 2022
Seriously? If I ask Google, I get e.g.:
- https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html
- https://www.mathworks.com/matlabcentral/answers/99124-how-do-i-pre-allocate-memory-when-using-matlab
For your code:
...
maxIter = 1000;
x = zeros(maxIter, 1);
y = zeros(maxIter, 1);
while norm(J) > e && i < maxIter
...
end
x = x(1:i); % Crop unused elements
y = y(1:i);
2 Comments
Jan
on 19 Nov 2022
What does "long" mean? Seconds or hours?
Symbolic calculations need some time. You can use the profiler to find the bottleneck:
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