Are my variables sliced?

Question

Sam 2013-3-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/67999-are-my-variables-sliced

Hello all. I'm trying to parallelize my code, and I'm having a devil of a time trying to understand what a sliced variable looks like. Below, I've included a cleaned-up version of the relevant parts of my code. If I'm not slicing the variables, please let me know what I can do to fix that. I think this might be important because each column of xdata is rather hefty. Thanks in advance.

x = nan(14,6) ;
parfor r = 1:14
       x0 = [param_struct.region(r).param1 ...
             param_struct.region(r).param2 ...
             param_struct.region(r).param3 ...
             param_struct.region(r).param4 ...
             param_struct.region(r).param5 ...
             param_struct.region(r).param6 ...
            ] ;   % x0 is a vector
       xdata = [data_struct(r).xdata1 ...
                data_struct(r).xdata2 ...
                data_struct(r).xdata3 ...
                data_struct(r).xdata4 ...
                data_struct(r).xdata5 ...
                ] ;   % xdata is a matrix
       ydata = data_struct(r).ydata ;
       x = lsqcurvefit(fun,x0,xdata,ydata) ;
end

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Answer 1

Shashank Prasanna 2013-3-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/67999-are-my-variables-sliced#answer_79401

Sam, you've probably already went through this page, but I will paste it here anyway:

http://www.mathworks.com/help/coder/ug/classification-of-variables-in-parfor-loops.html#btfitu2-18

The slicing happens is there is first-Level indexing. In this case param_struct is not sliced because the whole param_struct is required to be passed to each worker.

data_struct(r).xdata1 is sliced. Which means under parfor, data_struct is sliced into 14 variables and sent off to workers. In the former case param_struct can't be sliced because it appears to parfor that all of it may be required.