The problem here is that the parfor machinery cannot tell that you are completely overwriting quantity and Quantity_av in your inner loops. (In fact, you might not be, it's impossible to tell from the code you posted). This leads the parfor machinery to conclude that those variables are being used in such a way as to cause a dependence between the order of iterations in the loop. (If you don't full clear out e.g. quantity, then on the second iteration of the parfor loop, the values computed in the first iteration are still present, and so might influence the result of the second iteration - that's not allowed).
Presuming you did intend to completely overwrite quantity and Quantity_av, then the fix is simple: initialise those variables like so:
parfor counter3=1:n3
for counter2=1:n2
for counter1=1:n1
Quantity_av = zeros(n1, 1);
for i=1:N
quantity = zeros(m, 1);
for k=1:m-1
quantity(k+1,1)=something;
end
Quantity_av(i,1)=sum(quantity)/m;
end
QT=horzcat(QT,Quantity_av);
end
end
end
This initialisation causes the parfor machinery to conclude that quantity and Quantity_av are temporary variables, and thus the loop can proceed.
