Groups   62 of 99+      julia-users › Result changes if I change the number of workers 4 posts by 3 authors      Eduardo Lenz    11 26 15   Hi.  I came across a very weird behaviour when using a very simple  parallel loop. The block is quite large and complex, but the idea is the following:   A   zeros some_dimension  A   convert SharedArray,A   sync  parallel for i 1:some_dimension         Lots of code, but with no function calls             A i   +  block_result  end  some computation with sdata A .  If I use 4 processes, I get one result. With 8 processes, a diferent result. Without parallel processing, another one.  I am probably losing something, but I think this is not the intended behaviour.   I am using jula 4.11, fedora 23 - 64 bits.  Thanks for your help.     Seth    11 26 15   Are you doing floating point calculations? Some FP operations aren't associative and therefore may appear different on successive runs of a parallel operation depending on what's summed first:  julia   0.1 + 0.2  + 0.3 0.6000000000000001   julia  0.1 +  0.2 + 0.3  0.6      Eduardo Lenz    11 26 15   Thanks Seth.  I have a LOT of floating point calculations inside this loop. So, there should be it !   Now I have to figure it out how to overcome it....if it is even possible :0   Thanks a lot !!      ele... gmail.com    11 26 15   Do any of your calculations depend on the values of A?  If so they will get different values depending in what order A i  is updated.  And the order depends on scheduling of the processes, which is not deterministic.   Cheers Lex