Parallel loop variable query

Good morning,

I am trying to run a genetic algorithm to find the best parameters for a denoising a signal using ALE. I have the code running fine but takes a long time so I am trying to run a part of it using parallel loops this is my code currently.

    parfor i=1:pop_size

        child=gen(i,:);

        for m=1:9

            ch3=ch_all(m,:);

            ntr = child(3)*floor((length(ch3)-child(1))/child(3));

            x = ch3(1:ntr);

            d = ch3(1+child(1):ntr+child(1));

            leak = 1; % No leakage

            h = adaptfilt.blms(child(2),child(4),leak,child(3));

            [y,e] = filter(h,x,d);

            [ps p f]=best_processing(e, Fs, 14.9,child(5));

            percent_inc(m)=ps;

        end

        percent_ave=median(percent_inc);

        percent_diff(i)=sum(percent_ave)

    end

I get the following warning - Parfor will not run due to the way the variable 'percent_inc' is used. Can anyone tell me why this is or what must be done to amend the code? As far as I can see the code isn't dependent on anything outside the loop and i have preallocated the variable before the loop. Any help will be greatly appreciated,

Thanks

Jack

Answer 1

[Edric Ellis]

PARFOR currently thinks you're re-using values in percent_inc from one iteration of the PARFOR loop to the next. You can fix this simply be pre-allocating percent_inc (a good idea anyway) like so:

parfor i=1:pop_size
    ...
    percent_inc = zeros(1, 9);
    for m = 1:9
        ...
        percent_inc(m) = ...;
    end
    ...
end

[jnaumann]

Thanks. I had preallocated the array but had daftly put it before the PARFOR.

Thanks again