Error: The variable voltages1 in a parfor cannot be classified.

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0460051 NCTU 2016-10-4

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https://ww2.mathworks.cn/matlabcentral/answers/305664-error-the-variable-voltages1-in-a-parfor-cannot-be-classified

回答： 0460051 NCTU 2016-10-6

采纳的回答： Marc Jakobi

在 MATLAB Online 中打开

Hello,this is my code.

It is not runing because "The variable voltages1 in a parfor cannot be classified." Why?

voltages1  = num2cell(zeros(1,256),1);
voltages2  = voltages1;
parfor i=1:8
       inputVoltage1 =readVoltage(a,'A0'); 
       inputVoltage2 =readVoltage(a,'A5');
       voltages1{256} = inputVoltage1;
       voltages2{256} = inputVoltage2;
       subplot(2,1,1) ;      
       [ax,h1,h2] = plotyy(times,voltages1{:},times,voltages2{:});
       %axis(ax(1),[0 1 0 5]);
       %axis(ax(2),[0 1 0 5]);
       set(h1,'xdata',times,'ydata',voltages1{:});
       set(h2,'xdata',times,'ydata',voltages2{:});
       set(get(ax(1),'Ylabel'),'String','I Channel');
       set(get(ax(2),'Ylabel'),'String','Q Channel');
       title('Time Domain');
       set(h1,'Linewidth',2);
       set(h2,'Linewidth',2);
       drawnow update;
       voltages1{1:255} = voltages1{2:256};
       voltages2{1:255} = voltages2{2:256};
end

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Answer 1

Marc Jakobi 2016-10-4

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https://ww2.mathworks.cn/matlabcentral/answers/305664-error-the-variable-voltages1-in-a-parfor-cannot-be-classified#answer_237266

在 MATLAB Online 中打开

The problem is the line

voltages1{256} = inputVoltage1;

You cannot set a fixed index of an array or a matrix in a parfor loop, since multiple parallel instances of the loop will conflict with each other, trying to set voltages1{256} to different values at the same time.

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0460051 NCTU 2016-10-5

编辑：0460051 NCTU 2016-10-5

Thanks,but I still feel confused. I did not use the variable i just for repeating 8 times.so who runs in parallel? And I had another problems.

An UndefinedFunction error was thrown on the workers for 'configurePin'. This might be because the file containing 'configurePin' is not accessible on the workers. Use addAttachedFiles(pool, files) to specify the required files to be attached. See the documentation for 'parallel.Pool/addAttachedFiles' for more details.

Caused by: Error using parallel_function>make_general_channel/channel_general (line 929) Undefined function 'configurePin' for input arguments of type 'double'.

I had no idea what it meant....

Marc Jakobi 2016-10-5

I think you want to use for instead of parfor. parfor is used for parallel computing and doesn't make much sense when generating figures.

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Answer 2

0460051 NCTU 2016-10-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/305664-error-the-variable-voltages1-in-a-parfor-cannot-be-classified#answer_237677

Really? The reason why I use the function of parfor is beacause I want to make it plot quickly. Now ,I made time and fequency domains respectively,but the sampling rate was slower than the LabView's. So,that's why I wanted to seek the faster way to replace the LabView.

Thanks for your answering,thank you very much, Marc.