Question

Suppose I have a heavy-duty workhorse of a function:

[a b c d] = lotsOfComputation();

In some use cases, I may only need one or two of its outputs. In those cases, I ignore the output with a ~. Is it possible to detect this from within the lostOfComputation function?

(Yes, I know the more elegant solution is a refactor into separate functions. I have already done this for the immediate use-case, but the question remained in my head.)

Answer 1

Sure, try nargout, it returns the number of output arguments. Well, actually that will work when the argument is omitted, but it will count ~ as an argument. Here’s an example:

function [a b c] = test()
  a=0;b=0;c=0;
  disp(nargout);
end

>> [a, b] = test();
   2
>> [~, b] = test();
   2
>> [~, ~, ~] = test();
   3

So perhaps the answer to your exact question is no, at least not with nargout.