which is a matlab function with optional input and output in matlab

To create a MATLAB function with optional input and output arguments, you can use the nargin and nargout functions to check the number of input and output variables, respectively.

Here's an example function that adds two numbers and returns the result only if the user specifies an output variable. Otherwise, the function simply displays the result:

main.m
function result = add_numbers(varargin)
% ADD_NUMBERS Adds together two numbers.
% 
%   RESULT = ADD_NUMBERS(A, B) returns the sum of A and B.
%
%   ADD_NUMBERS(A, B, 'Display') displays the sum of A and B, but does not
%   return a value.
%
%   Examples:
%
%       result = add_numbers(2, 3)     % Returns 5
%       add_numbers(2, 3, 'Display')   % Displays '5'
%

% Check number of input arguments
nargs = length(varargin);
if nargs < 2
    error('Not enough input arguments.');
end

% Check number of output arguments
nargoutchk(0,1);

% Extract input arguments
A = varargin{1};
B = varargin{2};

% Calculate result and display or return it
result = A + B;
if nargs > 2 && strcmpi(varargin{3}, 'Display')
    disp(result);
else
    return;
end
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In this example, the nargoutchk function is used to ensure that only one output variable is assigned when the function is called with the optional Display argument. The strcmpi function is used to check if the third input argument is the string 'Display'.

Note that the use of optional arguments in MATLAB functions can sometimes make the code less readable and harder to maintain. In general, it's best to avoid them if possible.