What the difference between using bracket and not.

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Hi I'm newbie of matlab.
function varargout = redplot(varargin)
[varargout{1:nargout}] = plot(varargin{:},'Color',[1,0,0]);
end
this code doesn't appear the error.
but
function varargout = redplot(varargin)
varargout{1:nargout} = plot(varargin{:},'Color',[1,0,0]);
end
this code shows the error.
i don't know why the last cod appears the error.
the difference between them is [ ].
what is the role [ ] in this code.
Thank you.

Accepted Answer

Stephen23
Stephen23 on 8 May 2020
Edited: Stephen23 on 5 Jun 2022
None of the answers explain why this works, nor even mentioned the useful-to-know name of this syntax.
The actual reason is because that syntax combines two different syntaxes together. These are:
1- multiple function outputs are always indicated by square brackets, the outputs are written in the form of a comma-separated list, e.g.:
[a,b,c,d] = somefun();
This is explained in the introductory tutorials:
2- one cell array can be converted to (or from) a comma-separated list using this syntax:
somecell{:}
which is equivalent to this comma-separated list:
somecell{1},somecell{2},somecell{3},...
Read more about how comma-separated lists work:
Combine these two different syntaxes into one, to allocate multiple function outputs into one cell array:
[somecell{:}] = somefun();
Add indexing as required.
PS: the syntax somecell{:}=somefun() is meaningless.

More Answers (1)

Fangjun Jiang
Fangjun Jiang on 8 May 2020
I think the fundenmental reason is that the function definition requires that the left side contains "[ ]" when there are multiple outputs. See "doc function".

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