parfor and nested loop

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huda nawaf
huda nawaf 2014-1-23
评论： huda nawaf 2014-1-24
hi,
can I use parfor with nested loop?
for ex.
parfor i=1:5
for j=1:2
%%whatever
end
end
should I use par with each for or with one.
please, I need somebody can solve my problem.
Thanks in advance

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回答（2 个）

Mischa Kim
Mischa Kim 2014-1-23
Hello huda, there are no nested parfor loops. Parallelization with parfor only works on the outermost loop.
  1 个评论
huda nawaf
huda nawaf 2014-1-24
thanks,
ok, do u mean it is not problem if i use parfor for outermost loop and the inside loop stay as it.
I just wonder because when I used parfor for only outermost loop, I did not find any improvement in terms of running time.
Please, I badly need that.

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Matt J
Matt J 2014-1-23
编辑：Matt J 2014-1-23
To combine the loops into a single parfor loop,
parfor k=1:10
[i,j]=ind2sub([5,2],k);
%%whatever
end
  3 个评论
显示 1更早的评论
Matt J
Matt J 2014-1-24
The effectiveness of parfor depends a lot on what you're doing inside the loop.
huda nawaf
huda nawaf 2014-1-24
yes, but I read if I have large array it is best to use spmd.
this function will distribute the array among workers.
but I have problem. Also I used pmode .
I did not find the efficiency of these functions. I hope to find simple example show me the difference between parallel and serial processing.
thanks

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