MATLAB: Sliced variable index problem for parfor

parforsliced variable

Hi, I'm trying to select some Items from a 4D matrix using a parfor, but I get the sliced variables error, can't figure what is wrong. The indexing is clearly independent for each loop, all values in Idx_ValidGM are different.
for ii=1:size(NumStories,1)
    X_index = (ii-1)*size(T_Obj,2)*size(Q,1)*(NumGM - size(Discard,1));
    for jj=1:size(T_Obj,2)
        X_index = X_index + (jj-1)*size(Q,1)*(NumGM - size(Discard,1));
        for kk=1:size(Q,1)
            X_index = X_index + (kk-1)*(NumGM - size(Discard,1));
            parfor ll = 1:NumGM
                if Idx_ValidGM(ll) > 0
                    Index = X_index + Idx_ValidGM(ll);
                    Y_in(Index) = MaxMuMat(ii,jj,kk,ll);
                end
            end
        end
    end
end

Best Answer

all values in Idx_ValidGM are different
PARFOR has no way of knowing that. In any case, there is a far easier solution not involving parfor:
       Lidx=Idx_ValidGM(ll) > 0;
       IdxValid=Idx_ValidGM(Lidx);
       data=MaxMuMat(:,:,:,Lidx);
    for ii=1:size(NumStories,1)
        X_index = (ii-1)*size(T_Obj,2)*size(Q,1)*(NumGM - size(Discard,1));
        for jj=1:size(T_Obj,2)
            X_index = X_index + (jj-1)*size(Q,1)*(NumGM - size(Discard,1));
            for kk=1:size(Q,1)
                X_index = X_index + (kk-1)*(NumGM - size(Discard,1));
                Index=X_index + IdxValid;
                Y_in(Index)=data(ii,jj,kk);
            end
        end
    end
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