parfeval evaluation is slow

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Poul-Erik Hansen 2025-4-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2176221-parfeval-evaluation-is-slow

评论： Walter Roberson 2025-4-15

I am using parfeval to calculate the eigenvalues of a matrix M with typical dimension of 1500x1500x100. The parfeval evaluations is slow since I read the output just after the evaluation of each matrix M(:,:,k) k=1,..,100. I want to store all the eigenvalues and eigenvectores in the variabel f and read the output after finishing the parfeval evaluation.

Current code:

eigMtr=complex(zeros(2*L,2*NumOfSlabs*L));
W=eigMtr;
W_1=complex(zeros(L,2*NumOfSlabs*L));W_2=W_1;
for k=1:NumOfSlabs
    f=parfeval(@eig,3,M(:,:,k));
    [Wt,Dt] = fetchOutputs(f);
    start=1+(k-1)*2*L;stop=2*k*L;
    eigMtr(1:2*L,start:stop)=sqrt(Dt);
    W1=Wt(1:L,:); 
    W2=Wt(L+1:2*L,:);
    W_1(:,start:stop)=W1;
    W_2(:,start:stop)=W2;
    W(1:L,start:stop)=W2;
    W(L+1:2*L,start:stop)=W1; 
end

I want to do something like this

for k=1:NumOfSlabs
    f=parfeval(@eig,3,M(:,:,k));
end

for k=1:NumOfSlabs
    [idx,Wt,Dt] = fetchNext(f)
    start=1+(k-1)*2*L;stop=2*k*L;
    eigMtr(1:2*L,start:stop)=sqrt(Dt);
    W1=Wt(1:L,:); 
    W2=Wt(L+1:2*L,:);
    W_1(:,start:stop)=W1;
    W_2(:,start:stop)=W2;
    W(1:L,start:stop)=W2;
    W(L+1:2*L,start:stop)=W1; 
end

Thanks for your help

Poul-Erik

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采纳的回答

Walter Roberson 2025-4-11

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2176221-parfeval-evaluation-is-slow#answer_1563530

在 MATLAB Online 中打开

Note the correction to the number of output arguements parameter in the parfeval() call

f = cell(NumOfSlabs, 1);
for k=1:NumOfSlabs
    f{k} = parfeval(@eig,2,M(:,:,k));
end
wait(f{1});
for k=1:NumOfSlabs
    [Wt,Dt] = fetchOutputs(f{k});
    start=1+(k-1)*2*L; stop=2*k*L;
    eigMtr(1:2*L,start:stop)=sqrt(Dt);
    W1=Wt(1:L,:); 
    W2=Wt(L+1:2*L,:);
    W_1(:,start:stop)=W1;
    W_2(:,start:stop)=W2;
    W(1:L,start:stop)=W2;
    W(L+1:2*L,start:stop)=W1; 
end