Matlab script is very very slow! Help me please!
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Hello! I am a student and I created a Matlab code that allows me to open many txt files in succession and perform these sums and other operations. The work that the code has to do is a lot but it is really too slow. I calculated that it would take two days to finish. I think there is some conflict. Please ask me to help me otherwise I will have to do all those operations by hand and it will be a disaster for me. Thanks to those who will help me
I enclose the code I wrote in a text file
3 Comments
Answers (2)
per isakson
on 26 Dec 2019
Edited: per isakson
on 26 Dec 2019
Why not just let it run over a weekend?
I've downloaded your files and invoked your script. I interrupted the execution during the fourth data file. The script consists of three nested loops. One statement in the innermost loop uses 90% of the execution time.
for ii = 1 : 512
...
for kk = 1 : 8760 % What about leap years?
...
for jj = 1 : 8760 % What about leap years?
R(ii,[1:5,8:27])=R(ii,[1:5,8:27])+intermedia(jj,[1:5,8,9,11:21,29:35]); % 90%
...
end
end
end
The innermost loop does a number of summations. Replacing the innermost loop by
R(ii,[1:5,8:27]) = sum( intermedia(1:8760,[1:5,8,9,11:21,29:35]), 1 );
is_positive = intermedia(1:8760,7)>0;
R(ii,6) = sum( intermedia(is_positive,7) );
R(ii,7) = sum( intermedia(not(is_positive),7) );
improves the speed of the script significantly. (You need to confirm that it returns the correct result.)
3 Comments
per isakson
on 26 Dec 2019
Did you try the profiler?
I don't think there are more low hanging fruits.
Rocco De Luca
on 27 Dec 2019
2 Comments
per isakson
on 27 Dec 2019
Assume that your original code with the three loops produce the expected result. Use that result as a reference. Each new version shall produce exactly (a floating point error is ok) the same result. That can be tested systematically with the Unit Testing Framework. If the results are identical and if there is enough variation in the data files, COMPLETOA20KM*, the new code is most likely correct. Are the results identical?
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