Problem 44345. MATLAB Counter

Created by Peng Liu

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1642 Solutions
231 Solvers

Last Solution submitted on Oct 18, 2021

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Problem Comments

8 Comments

8 Comments

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Sunke on 18 Oct 2017

My function works directly as described - but does not manage to pass the test suite ... what is wrong?

%%
function varargout = counter(varargin)
persistent add base
if isempty(varargin)
base = base + add;
varargout{1} = base;
end
if numel(varargin) > 1
add = varargin{2};
base = varargin{1}-add;
end
end

Peter Cook on 25 Oct 2017

For anyone needing a gentle refresher (like I did) on nested anonymous functions:
https://www.mathworks.com/matlabcentral/cody/problems/24-function-iterator

David Verrelli on 15 Nov 2017

Cody's Problem 24 might be of relevance, but note that so far very few of the correct solutions to the present problem (Problem 44345) have used anonymous functions, whereas all of the correct solutions have used named functions (some nested, some not).

David Verrelli on 15 Nov 2017

Correction: there is a solution here (Solution 1308690) which only uses an anonymous function, without calling a named user function.

David Verrelli on 15 Nov 2017

Either (or both) of the following pages may be of interest in tackling this problem: https://mathworks.com/help/matlab/matlab_prog/nested-functions.html and https://mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html .

Berkan Höke on 19 Dec 2017

It's the best problem in Cody:Easy

kim9091 on 17 Jan 2019

You can also use class definition to solve it, amazing!

Alex on 31 Aug 2020

the tests can be strengthened a bit, to allow multiple counters

g = counter(1,2);
h = counter(3,5);
assert(isequal([1 3 5 3 8 13], [g() g() g() h() h() h()]));

Solution Comments

Solution 5166953

1 Comment

1 Comment

李君 on 25 Mar 2021

persistent and function handle?

Solution 1877072

1 Comment

1 Comment

Evan on 17 Jul 2019

Due to the use of persistent variables and the conditional statements used, this solution would fail if the test suite were modified to include two tests in a row with the same increment value.

Solution 1399429

Solution 1397647

1 Comment

1 Comment

Atsushi Ueno on 29 Dec 2017

Solution 1380961

1 Comment

1 Comment

Roche de Guzman on 15 Dec 2017

I just learned how to use the combined fx handle and nested fx!

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cody5 nested function

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Problem 44345. MATLAB Counter

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Problem 44345. MATLAB Counter

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