MATLAB: What does the varargin function do and what does varargin{:} mean

Question

For example: [varargin{:}] = convertStringsToChars(varargin{:});

Answer 1

"What does the varargin function do..."

varargin is not a function, it is a cell array which contains any number of optional input arguments:

https://www.mathworks.com/help/matlab/ref/varargin.html

"... and what does varargin{:} mean?"

That syntax creates a comma-separated list from the cell array varargin:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

https://www.mathworks.com/company/newsletters/articles/matlab-tips-and-tricks-exploiting-the-comma-separated-list-vectorizing-cell-array-and-structure-references.html

So your example is equivalent to this:

[varargin{1},varargin{2},...,varargin{end}] = convertStringsToChars(varargin{1},varargin{2},...,varargin{end});