Info

This question is closed. Reopen it to edit or answer.

Help: restructuring parfor

1 view (last 30 days)
Pramit Biswas
Pramit Biswas on 6 Apr 2018
Closed: MATLAB Answer Bot on 20 Aug 2021
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.
  1 Comment
Adam
Adam on 6 Apr 2018
What are the warnings you get when you try?

Answers (1)

Bhavanithya Thiraviaraja
Bhavanithya Thiraviaraja on 17 Apr 2018
Edited: Bhavanithya Thiraviaraja on 17 Apr 2018

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.

Tags

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!