parfor for double iteration??

Question

Jinsoo 2013-8-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/85399-parfor-for-double-iteration

采纳的回答： Edric Ellis

在 MATLAB Online 中打开

Dear, I want to make a matrix G(m, n) as follows:

gamma = sqrt(sqrt(k/(E*I))); % gamma

G = zeros(length(x),length(qusi));

parfor n1 = 1:length(x)

    for n2 = 1:length(qusi)
        qua = gamma*abs(qusi(n2)-x(n1))/sqrt(2);
        G(n1,n2) = (gamma/(2*k))*exp(-qua)*sin(qua + pi/4);   % G(x,qusi)
    end

end

However, the error come up as follows:

Error using testsquare_test (line 53)

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

See Parallel for Loops in MATLAB, "Overview".

I can't understand it. How should I do?

Could you please help me?

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Khoo 2013-8-23

Are you using the parallel computing from matlabpool? parfor is same as for-loop but it's in parallel computing.

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Answer 1

Edric Ellis 2013-8-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/85399-parfor-for-double-iteration#answer_95209

在 MATLAB Online 中打开

Unfortunately, PARFOR doesn't understand how you're accessing 'G' even though you are using it in an order-independent way. What you need to do is build up a temporary row, and then assign it to the row of 'G' all in one go:

parfor n1 = 1:length(x)
  tempRow = zeros(1, length(qusi));
  for n2 = 1:length(qusi)
    qua = gamma*abs(qusi(n2)-x(n1))/sqrt(2);
    tempRow(n2) = (gamma/(2*k))*exp(-qua)*sin(qua + pi/4);
  end
  G(n1, :) = tempRow;
end