parfor error with 3D matrix

Hello everyone,

I am using the parfor loop for the 3D matrix. When I am executing my parfor loop and getting this error "Error: The variable TEST1 in a parfor cannot be classified. See Parallel for Loops in MATLAB, "Overview". I am replacing the zero value with nan in the loop. Any suggestion regarding this. Your help in this regard will be highly appreciated.

data  = rand (20,10,10);
data1 = rand (20,10,10);
parfor ii=1:20
    ii
    for jj=1:10
        jj
            TEST1 (ii,jj,:) = data(ii,jj,:).*data1 (ii,jj,:);
            TEST1 (TEST1==0) = nan;
        end
 end

Answer 1

[Matt J]

Move that line outside the loop.

parfor ii=1:20
    ii
    for jj=1:10
        jj
            TEST1 (ii,jj,:) = data(ii,jj,:).*data1 (ii,jj,:);

        end
end

TEST1 (TEST1==0) = nan;

Answer 2

[sunny kant]

Thanks you Matt for your suggestion on the code. However, I am applied the same thing, but when I am applying TES1 (TEST1==0) = nan inside the parfor loop in the code, it gives error. Can you suggest me that why it is happing.

[Walter Roberson]

TEST1(TEST1==0) = nan;

inside the parfor loop would be an attempt to have the worker modify all of the variable TEST1, not just the part that is allocated to the loop. You should confine yourself to just the current worker's values

T2 = TEST1(ii,:,:);
T2(T2 == 0) = nan;
TEST1(ii,:,:) = T2;

[Matt J]

Additionally

TEST1 (TEST1==0) = nan;

is an operation that Matlab already does in a fast, parallelized manner without explicit loops. You should reserve parfor only for things that cannot easily be replaced with vectorized expressions.

[Matt J]

sunny kant's comment moved here

Thanks Walter for explaining me why my code is not working. As you suggested, I appllied for my code, and now it is working. Thanks for your suggestion on my code and clearing my doubts.