MATLAB Answers


Error using gpuArray/subsasgn

Asked by Tiki Tiki on 13 Jun 2019
Latest activity Commented on by Edric Ellis
on 17 Jun 2019
Hi everyone
I am working on GPU. I have a problem with it. I try to assign to a gpu Array. but i get this error.
it is working on CPU, however GPU is not.
"Error using gpuArray/subsasgn
When assigning into a GPUArray, the subscripts must contain unique values. Subscript 1 contained repeated values."
can you tell me how to solve this error?


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1 Answer

Answer by Edric Ellis
on 14 Jun 2019
 Accepted Answer

You can avoid this error by ensuring that your subscript contains only unique values, using the MATLAB function unique. For example:
gvec = gpuArray(1:100);
% Indexes to assign - contains repeated indices
idxs = [1 1 2 3];
% Values to assign
vals = rand(1, 4);
% This would get an error - the assignment happens in parallel on the GPU,
% so which value should gvec(1) get - vals(1) or vals(2)?
%gvec(idxs) = vals;
% Use UNIQUE on idxs
[uniqueIdxs, locOfUniqueIdxs] = unique(idxs);
% Assign using only the unique indices, and the corresponding values
gvec(uniqueIdxs) = vals(locOfUniqueIdxs);


my problem is "Error, gpuArray/subsasgn
Sparse gpuArrays are not supported for this function."
how to solve that?
Edric Ellis
on 17 Jun 2019
You cannot modify sparse gpuArray data once you have put it on the GPU - you should set up the data as you want it to be, then send it to the GPU.

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