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

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Stef
Stef 2017-11-11
评论： Jan 2017-11-12
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))

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回答（1 个）

Jan
Jan 2017-11-11
编辑：Jan 2017-11-11
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.
  2 个评论
Stef
Stef 2017-11-11
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
Jan 2017-11-12
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.

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