How much data does an array take?

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Alec Bledsoe
Alec Bledsoe on 4 Nov 2023
Commented: Walter Roberson on 4 Nov 2023
My question is pretty much entirely in the title. I am curious about how matlab stores data and specifically how much data an nxn array takes to store. Is each element of the array an individual 8 byte double so the size is 8*n^2 bytes?

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James Tursa
James Tursa on 4 Nov 2023
Edited: James Tursa on 4 Nov 2023
The data is held in contiguous memory, so yes for a full real double an NxN matrix would take 8*N^2 bytes for the data. Then there is a variable header that contains info such as class, dimensions, data pointers, etc. That takes an additional 132(?) bytes or so per variable. The actual header amount can vary from release to release, and I haven't checked lately what it is currently.
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Alec Bledsoe
Alec Bledsoe on 4 Nov 2023
Got it thank you. How do I check the header size?
Walter Roberson
Walter Roberson on 4 Nov 2023
https://www.mathworks.com/matlabcentral/answers/2010767-struct-function-in-matlab
My answer there analyzes struct.
96 bytes to describe a variable. 8 bytes pointer to the data. Another 64 bytes to hold the variable name.

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