Help: restructuring parfor

Question

Pramit Biswas 2018-4-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/393054-help-restructuring-parfor

关闭： MATLAB Answer Bot 2021-8-20

   totpV=5;
   vars = rand(totpV,2);
   for loop1=1:100
      for loop2=1:totpV  % Make this loop2 parallel using parfor
         parameter=vars(loop2,:,loop1);
         result(loop2,loop1)=feval('sum',parameter);  % sample function
         if min(result(loop2,:))<=result(loop2,loop1)
            best=result(loop2,loop1);
         end
         vars(loop2,:,(loop1+1))= vars(loop2,:,loop1) + rand(1,2).*best;
      end
   end

I want to process loop2 parallelly, however, not getting how. From This page, probably this is due to Sliced Variables. Any idea to restructure?

Errors: The PARFOR loop cannot run due to the way variable 'vars', 'result' is used.

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Adam 2018-4-6

What are the warnings you get when you try?

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Answer 1

Bhavanithya Thiraviaraja 2018-4-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/393054-help-restructuring-parfor#answer_315549

编辑：Bhavanithya Thiraviaraja 2018-4-17

在 MATLAB Online 中打开

There seems to be a dependency between the iterations in the line

min(result(loop2,:))<=result(loop2,loop1)

In parfor, the iterations are performed on independent MATLAB workers and hence it requires 'No Dependency'. In this case, the min(result(loop2,:)) seems to use the previously calculated values also, hence making it dependent.

Refer https://de.mathworks.com/help/distcomp/ensure-that-parfor-loop-iterations-are-independent.html for examples!

The dependency has to be broken without affecting the algorithm to use parfor.