Sliced variable index problem for parfor

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

Answer 1

[Matt J]

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

[Jose Ramon Silos de Alba]

Thank you

[Matt J]

You're welcome, but please click "Accept" to close the question.

[Walter Roberson]

"all values in Idx_ValidGM are different"

parfor does not even know that the values are all positive. It cannot prove that all of the output locations are unique.