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

2 views (last 30 days)
0460051 NCTU on 4 Oct 2016
Answered: 0460051 NCTU on 6 Oct 2016
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
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

Marc Jakobi on 4 Oct 2016
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.
Marc Jakobi on 5 Oct 2016
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.

0460051 NCTU on 6 Oct 2016
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.

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