Variable input using a flag

I'd like to create a function that has a variable number of return arguments based on the value of a flag, having a fixed number of input parameters.

    [out1, out2] = myFun(inp1, inp2, 'a');
    [out1, out2, out3] = myFun(inp1, inp2, 'b');

I tried using varargout but haven't managed to successfully accomplish what I want to do.

Answer 1

[Stephen23]

MATLAB returns arguments based on demand, so you can simply define all three of them:

function [out1, out2, out3] = myFun(inp1, inp2)
out1 = 1;
out2 = 2;
out3 = 3;

and then call it with either two or three output arguments. Try it!

[Gaetano Quattrocchi]

Thanks Stephen for your quick reply, but this wasn't exactly what I was searching for. Thanks anyway!

[Walter Roberson]

function varargout = myFun(inp1, inp2, flag)
  if strcmpi(flag, 'a')
    varargout{1} = 1;
    varargout{2} = 2;
  elseif strcmpi(flag, 'b')
    varargout{1} = 11;
    varargout{2} = 12;
    varargout{3} = 13;
  else
    varargout(1:nargout) = {[]};
  end

[Stephen23]

Or the same without varargin:

function [y1,y2,y3] = myFun(inp1, inp2, flag)
if strcmpi(flag, 'a')
  y1 = 1;
  y2 = 2;
elseif strcmpi(flag, 'b')
  y1 = 11;
  y2 = 12;
  y3 = 13;
else
  [y1,y2,y3] = deal([]);
end

[Gaetano Quattrocchi]

Thank you both for the clear answer!

[Walter Roberson]

The very minor difference between the varargout version and the y1, y2, y3 version is for cases such as

[A, B, C, D, E, F, G] = myFun(inp1, inp2, 'nonsense')

The varargout version will set all of the outputs to [] but the y1, y2, y3 would error because the 4th output onward were not set.

Both versions would fire an error for

[A, B, C] = myFun(inp1, inp2, 'a')

for not having set the third output.

You could also consider

function varargout = myFun(inp1, inp2)
  if nargout == 2
    varargout{1} = 1;
    varargout{2} = 2;
  elseif nargout == 3
    varargout{1} = 11;
    varargout{2} = 12;
    varargout{3} = 13;
  else
    varargout(1:nargout) = {[]};
  end

which detects how many outputs were requested and can do different things depending on the number of outputs.