Problem 42633. Cumulative maximum of an array

Created by Matthew Eicholtz

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Find the cumulative maximum of an array without using the built-in function cummax (and a few others). Your function should act identically to cummax, allowing the same inputs.
Examples
If X = [0 4 3
        6 5 2]
cumax(X,1) is [0 4 3  and cumax(X,2) is [0 4 4
               6 5 3]                    6 6 6]
cumax(X,1,'reverse') is [6 5 3  and cumax(X,2,'reverse') is [4 4 3
                         6 5 2]                              6 5 2]
Also,
cumax([8 9 1 10 6 1 3 6 10 10]) returns [8 9 9 10 10 10 10 10 10 10]
cumax([8 9 1 10 6 1 3 6 10 10]') returns [8 9 9 10 10 10 10 10 10 10]'
See also cumin.

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Last Solution submitted on Dec 23, 2025

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3 Comments

Jean-Marie Sainthillier on 7 Jul 2022

There is a problem is the first test.
Remove the assert(isempty(strfind(filetext,'max'))) because the name of the function cumax contains the string max.

Thank you.

Christian Schröder on 7 Oct 2022

@Matthew, could you be so kind and fix the first test? As it is, it is impossible to solve this problem since the function name "cumax" itself contains the string "max".

This also makes it impossible to obtain the Matrix Manipulation III badge.

Dyuman Joshi on 9 Oct 2022

The test suite has been updated temporarily.

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Problem 42633. Cumulative maximum of an array

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Problem 42633. Cumulative maximum of an array

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