How to solve "Error while using repmat : out of memory"
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Hi all,
I was dealing with codes for image processing, where I need to use "repmat" function to create a big 5-d matrix, in a size of [116 116 72 64 64].
And it will give "out of memory" error.
The slice of code is shown below, it will give error when trying to assign new value to w (2nd row):
sq = repmat(sq, [1, 1, 1, 1, nd]);
w = repmat(reshape(w, [1, 1, 1, nd, nd]), [sx, sy, sz, 1, 1]);
raw = cat(4, s0, squeeze(sum(sq .* w, 4)));
Here , before these lines,
sq in [116 116 72 64]
w in [64, 64]
nd = 64, sx = sy = 116, sz = 72
What make things wield is, the size of matrix "sq" is in the same shape. And there will be no error when executing the first line of code, which means we could allocate enough space for a matrix in a size of [116 116 72 64 64].
As you can see, what I wanna do is creating w in the same shape as sp, and perform a element-wise multiplication. But the 2nd line will not work.
I tried to pre-allocate an empty matrix instead, by using zeros, but again get "out of memory" error.
Can anybody help me?
Thanks.
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Matt J
2019년 1월 4일
편집: Matt J
2019년 1월 4일
Forget about repmats. Use the original sq and w as follows,
tmp=reshape( reshape(sq,[],nd)*w , size(sq) );
raw = cat(4, s0, tmp);
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Matt J
2019년 1월 8일
편집: Matt J
2019년 1월 8일
Then, reshaped sq is 62005248*64, and w is 64*64. Since matlab uses double as default, it'll raise memory exceeding error when performing multiplication.
First of all, no, if you multiply a single matrix by a double matrix, the result will be a single matrix.
Secondly, the memory consumption that you've described doesn't add up. You said in your initial post that you had just enough memory to hold the repmatted sq, which was of dimensions [116 116 72 64 64]. That had to consume at least 4 GB. If you had enough memory for that, you should have plenty of memory to spare (now that you're not using repmat) to hold the original sq in single or even double format. In single format, this only consumes 0.25 GB:
>> whos sq
Name Size Kilobytes Class Attributes
sq 116x116x72x64 242208 single
If you're still getting out of memory errors, my suspicion is that you are still using repmat somewhere.
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