fminbnd in parallel: no gain

Question

martin 2014-1-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113501-fminbnd-in-parallel-no-gain

编辑： Matt J 2014-1-24

I want to minimize a function using fminbnd on a 32-core Linux machine (running Ubuntu 13.10+matlab2013a). I do the following:

>>matlabpool
Starting matlabpool using the 'local' profile ...
connected to 12 workers
>>optim_fminbnd=optimset('fminbnd');
>>tic
>>disp('With parallelization:')
With parallelization:
>> fminbnd(@localstrul_valuespectral,0,359,optimset(optim_fminbnd,'UseParallel','a
lways'))
ans =
    221.8743
>>toc
Elapsed time is 7.124580 seconds.
>>tic
>>disp('Without parallelization:')

Without parallelization:

>>fminbnd(@localstrul_valuespectral,0,359,optimset(optim_fminbnd,'UseParallel','ne
ver'))
ans =
    221.8743
>>toc
Elapsed time is 7.785863 seconds

that is to say there is no gain in speed (sometimes the non-parallel version is marginally faster). Do I set the parameters wrong?

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Answer 1

Alan Weiss 2014-1-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113501-fminbnd-in-parallel-no-gain#answer_122046

fminbnd is a serial algorithm. There is no gain possible using parallel processing. In fact, look at the options for fminbnd, and you see that fminbnd does not use the UseParallel option.

Alan Weiss

MATLAB mathematical toolbox documentation