Avoid copy when slicing large vector

Question

Son Hua 2011-3-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2817-avoid-copy-when-slicing-large-vector

We know that MATLAB employs the copy-on-write mechanism for handling arrays. For example

a = zeros(10^6);
b = a; % Just a pointer assignment.
b = a(123:end); % Slicing causes b to copy values from a.

My question is, can I have something similar to b = a(123:end), but no copy is performed? My vector a is quite large (much larger than 10^6 elements), so slicing causes overhead. Can I create a C MEX-file that assign a pointer of a+123 to b and return the array without copying?

Thanks.

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Answer 1

Jan 2011-3-9

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2817-avoid-copy-when-slicing-large-vector#answer_4363

You can look into inplacecolumnmex.c of Bruno's http://www.mathworks.com/matlabcentral/fileexchange/23576-minmax-selection .

It works, but has a limited stability only: If the program stops with an error, before the arrays are freed, Matlab crashs due to a confused memory manager.

If you are familar with C-Mex files, implementing the functions operating on your intermediate arrays, would be much more reliable.