MATLAB: Access outputs of functions with multiple outputs

anonymous functionhackMATLABtrickvarargout

Dear All,
I would like to find a functional way to access outputs of functions with multiple outputs. Assume I have a function "twout" defined in a m-file as follows
function [foo, bar] = twout(x, y)
 foo = x+y;
 bar = x-y;
end
I would like now to access the SECOND output "bar" from a function handle, i.e. I am looking for a function (or something which can be put into an anonymous function) called "somemagic" say, such that an anonymous function can be defined as
anoneout = @(x,y)( somemagic( twout(x, y) )
and the call
@anoneout(1,2)
produces -1.
It is clear that I can always
  • write anoneout into a separate .m-file where I make a proper call to twout
  • switch "foo" and "bar" in the function definition.
  • return a structured data type instead of 2 outputs
My question is really whether these workaroounds are indeed the only solutions.
Thanks
gg

Best Answer

There is a way to do it, but I am reluctant to share it because I don't think it is worthwhile to program this way. I cannot think of any reason one would want to do this, except to see if it could be done. Since I am that kind of curious person, I will show how to do it, but again I think you should go another route!
>> f = @(x,y,r) evalin('caller',[sprintf('[~,x]=twout(%.15f,%.15f);',x,y),r,'=x;'])
>> f(2,3,'r')  % Third arg is a string: [~,r] = twout(2,3)
>> r
r =
      -1
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