MATLAB: Using fminsearch on a Function with Multiple Outputs

anonymous functionsfminsearchmultiple outputsnested functions

Hi,
I have a function called calculateValues, which is stored in a seperate .m file, and takes two inputs ( x and a), while producing 3 outputs ( out1, out2, and out3):
[out1, out2, out3] = calculateValues(x,a);
I would now like to use MatLab's fminsearch to minimise the third output (out3) of my function calculateValues with respect to the variable x (leaving a as just a constant, i.e. not varied as part of the optimisation). Therefore I wanted to do something like the following:
out3min = fminsearch(@(x)calculateValues(x,a),x0);
However, it seems like the default output to be minimised is out1. I guess I need to force the anonymous function @(x)calculateValues(x,a) to return only out3. Does anyone have any suggestions how it can be done? Maybe a way to nest anonymous functions to achieve this?
Many Thanks

Best Answer

It is not possible to use an anonymous function to select a particular output from a function. You need to use an actual function.
   function result = lastoutput(fun, varargin)
     n = nargout(fun);
     outs = cell(1,n);
     [outs{:}] = fun(varargin{:});
     result = outs{end};
And now you can
out3min = fminsearch( @(x)lastoutput(@calculateValues,x,a), x0);
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