How do I make this loop faster?

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jakobjakob 2018-6-9

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https://ww2.mathworks.cn/matlabcentral/answers/404851-how-do-i-make-this-loop-faster

关闭： Jan 2018-6-9

alldata.mat

在 MATLAB Online 中打开

for j= 1:240
  k=index_aanname(j);
  for l=1:length(alldata);
    while ((strcmp(alldata(l,3), SA{j})) && ...
          ((TA(1,j) - alldata{l,1}) <= 10.0) && ...
          (strcmp(alldata(l,4), 'Voor'))) == 1
      B(l) = (tijdnum(l));
    end
  end
end

How do I make this loop faster? It is during way too long...

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dpb 2018-6-9

More than likely don't need to loop over l at all but as written B will contain results for those values of l that are anywhere in the combination of the SA/TA arrays. Is this the intended result?

Also, as written the test for TA is signed; is that also intended to be one-sided?

Without rest of data arrays nobody here can test/play around with the problem.

As for speed, was B preallocated? As is, will "grow" dynamically which is a speed bottleneck of first order.

Jan 2018-6-9

Please post all input data such that we can run the code. Currently the posted code is meaningless, because the while loop does not stop: The condition is not modified by the body of the loop.

It is not useful to ask for the acceleration of a not running code. Please edit the question and fix it.

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