parfor indexing and order

[a,b,c]=size(Mask);  % a=b=c=3;

parfor i=1:size(Mask,3)
  i
end

I was expecting to see i=1,i=2,i=3 in a sequence as one would see in a for loop but it is giving me i=3,i=2,i=1 . This is in reverse order. I cant figure out the reason.

Answer 1

[xplore29]

Although I am not using parfor for variable display purpose but I am curious to know that if I try to display the variable like this in parfor the order will always be reverse (like in my example) or it can be random.

Answer 2

[Edric Ellis]

PARFOR loops can run in parallel, and as such, the iterations might run in any order. You should not rely on this order. In particular, as you have observed, PARFOR starts running iterations in reverse order.