why my empty cell array taking 104 bytes instead of 112 bytes..?

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OMKARAM RAJESHWARA RAJU
编辑： Walter Roberson 2020-9-6
Hello,
it is mentioned in the document that,
an empty cell array will take
30 bytes for 32 bit systems
& 112 bytes for 64 bit systems.
i got confused why my 64 bit system is taking 104 bytes of memory for an empty cell array..
can someone please explain me..?
Thanks in advance ..!

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采纳的回答

Bruno Luong
Bruno Luong 2020-9-6
编辑：Bruno Luong 2020-9-6
A = {[]}
is NOT an empty cell, it's 1 x 1 cell contains an empty array.
An empty cell is
A = {}
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Bruno Luong
Bruno Luong 2020-9-6
编辑：Bruno Luong 2020-9-6
Sorry, I can't answer you.
I don't know what whos command exactly display for BYTES or the internal mechanism when CELL or {} command is invoked.
Bruno Luong
Bruno Luong 2020-9-6
编辑：Bruno Luong 2020-9-6
I read the doc and test on 2 MATLAB versions 2018b and 2020a. The 112 bytes of header size seems to be applicable to R2018b and 104 bytes for 2020a
R2018b
>> A={[]}
A =
1×1 cell array
{0×0 double}
>> whos
Name Size Bytes Class Attributes
A 1x1 112 cell
And R2020a
>> A={[]}
A =
1×1 cell array
{0×0 double}
>> whos
Name Size Bytes Class Attributes
A 1x1 104 cell
So the document you posts is not up-to-date.

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Image Analyst
Image Analyst 2020-9-6
Cell arrays take a huge amount of overhead. Don't use them unless you have to, which means you'll have different kinds of variables in each cell. Otherwise use a double array if they're all numbers, or a table if it's a mixture of variable classes (e.g. strings and numbers) but each column will be all of the same class.
See the very first item on the FAQ: What is a cell array?

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