Pack/Unpack Logicals

Version 1.0.0.0 (2.82 KB) by James Alaly
Compress large logical variables to one bit per element, instead of the usual 8.
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1.3K Downloads
Updated 28 Dec 2004

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MATLAB (6.5 at least) stores logical variables in memory as 8 bits per element, even though only one bit is required. This means a 512x512x100 logical mask takes up 25 MB of memory. By compressing this mask the same amount of data takes only 3MB.

A limitation is that compressed logicals are stored in a struct array, and cannot be operated on in a meaningful way without unpacking them. I use this compression to store many large masks in memory, and then I unpack them when I am ready to use them.

Cite As

James Alaly (2026). Pack/Unpack Logicals (https://www.mathworks.com/matlabcentral/fileexchange/6586-pack-unpack-logicals), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R13
Compatible with any release
Platform Compatibility
Windows macOS Linux
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Version Published Release Notes
1.0.0.0

Updated to store size of original logical vector/array in the packed data structure. Idea by Iram Weinstein.

Also added a function isPackedLogical to test if a variable needs to be unpacked.