Problem 56060. Sub-Diagonal Sum

Given a (m x n) matrix and a value r {1,-1}, change every element to the sum of the diagonal led by the element.
r=1 > regular diagonal (top left to bottom right)
r=-1 > flipped/cross diagonal (top right to bottom left)
in=[1 2 3 4
5 6 7 8
1 3 2 0]
r=1
out=[9 9 11 4
8 8 7 8
1 3 2 0]
%explaination
(1,1) diagonal - [1 6 2], sum = 9
(1,3) diagonal - [3 8], sum = 11
(2,1) diagonal - [5 3], sum = 8
(2,4) diagonal - [8], sum = 8
in=[1 -2 3 -4
5 -6 7 -8
1 3 -2 0]
r=-1
out=[1 3 -2 6
5 -5 10 -10
1 3 -2 0]
%explaination
(1,1) diagonal - [1], sum = 1
(1,3) diagonal - [3 -6 1], sum = -2
(2,2) diagonal - [-6 1], sum = -5
(2,4) diagonal - [-8 -2], sum = -10
Solve

Solution Stats

38.71% Correct | 61.29% Incorrect
Last Solution submitted on Sep 22, 2025

Problem Comments

Solution Comments

Show comments

Problem Recent Solvers11

Suggested Problems

More from this Author43

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!