How to use just one output out of a function with several outputs in an equation?

I have a function with three outputs depending on x. I want to use one of these three say B(x) in an equation:

function [ A,B,C ] = f( x )
Equation=1+x+B(x)

How do I have to code the equation? what I want to have is something like this (does not work):

Equation=1+x+f(B(x))

Answer 1

[Jan]

You have to do this in two lines:

[~, B]   = f(x);
Equation = 1 + x + B(x);

Of course you could write a function, which extracts a certain output only, but this is less clear:

function X = SelectOutput(N, Fcn, varargin)
[Out{1:N}] = Fcn(varargin{:});
X          = Out{N};
end

Then:

Equation = 1 + x + SelectOutput(2, f(x));

I don't think, that this is an advantage.

[Stef]

But why should I write a function then? (I have the task to do so) Because then I could just do it like this:

b=@(x) 3*x

[Jan]

I cannot follow you. This code is unclear already:

function [ A,B,C ] = f( x )
Equation=1+x+B(x)

Why does "B" appear in the output, when it is used inside the function? Where do A and C come from?

Then "b=@(x) 3*x" seems to be completely unrelated. Please start from scratch and explain, which problem you try to solve. Append this information by editing the original question.