Problem 413. Back to basics 23 - Triangular matrix

Created by Alan Chalker
Appears in Cody Problems in Japanese

Difficulty:Rate

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Covering some basic topics I haven't seen elsewhere on Cody.

Given an input matrix, return a matrix with all elements above and to the right of the main diagonal set to zero. Example:

input = [ 1 1 1 1; 1 1 1 1; 1 1 1 1; 1 1 1 1]
output = [1 0 0 0; 1 1 0 0; 1 1 1 0; 1 1 1 1]

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1948 Solutions
1035 Solvers

Last Solution submitted on Mar 17, 2025

Last 200 Solutions

Problem Comments

3 Comments

3 Comments

Chad Gilbert on 11 Jul 2013

Your test suite doesn't really match the problem statement. The tests require matrices with *exactly* all elements abot the main diagonal to be 0 *and* all elements on or below the main diagonal to be 1.

goc3 on 24 Feb 2017

Additional test cases have been added.

Diogo Carvalho on 10 Feb 2019

Running this on octave returns the correct results yet the page still says I'm wrong.
function y = triangMatrix(x)
for i=1:rows(x);
for j=1:columns(x);
if j>i;
x(i,j)=0;
else
endif
endfor
endfor
disp(x)
endfunction

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Project Euler I

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