Problem 581. Function composition

Created by David Hruska

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Write a function that accepts two function handles f and g and returns the composition h. That is,

h = (f o g)(x) = f(g(x))

Example:

>> f = @(x)x^2;
>> g = @(x)x+1;
>> h = composeFcn(f,g);
>> h(3)
ans =
  16

because (3+1)^2 = 16.

Solve

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Last Solution submitted on Apr 22, 2025

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Jihye Sofia Seo on 16 Feb 2017

My code runs fine on my local machine, but I get error messages when I try it here.

Jihye Sofia Seo on 16 Feb 2017

Error using compose (line 85) First argument must be a string array, character vector, or cell array of character vectors. Error in TestPoint1 (line 3) h = compose(f,g);

yurenchu on 25 Apr 2017

To the creator of this problem: please rename this function in your test suite. "Compose" is already a built-in MATLAB function.

David Hruska on 26 Apr 2017

Changed the function name to composeFcn to avoid clashing with the compose built-in function. Let me know if you're still having trouble!

Ned Gulley on 26 Apr 2017

I guess the name needed changing, but be aware that if we ever re-score old entries, everyone who passed before the name change will now fail, since they will now be calling the wrong function.

yurenchu on 27 Apr 2017

Thanks, David Hruska!

善翔韩 on 28 Aug 2022

function h = composeFcn(f,g)
syms x
x=g(x);
h=matlabFunction(f(x));
end
I am so confused where i was wrong?

Dyuman Joshi on 28 Aug 2022

@善翔韩, syms is a part of symbolic toolbox and toolboxes are not available on cody.

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Problem 581. Function composition

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