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# Program to check if matrix is upper triangular

• Difficulty Level : Basic
• Last Updated : 26 Apr, 2021

Given a square matrix and the task is to check the matrix is in upper triangular form or not. A square matrix is called upper triangular if all the entries below the main diagonal are zero. Examples:

```Input : mat = {{1, 3, 5, 3},
{0, 4, 6, 2},
{0, 0, 2, 5},
{0, 0, 0, 6}};
Output : Matrix is in Upper Triangular form.

Input : mat = {{5, 6, 3, 6},
{0, 4, 6, 6},
{1, 0, 8, 5},
{0, 1, 0, 6}};
Output : Matrix is not in Upper Triangular form.```

## C++

 `// Program to check upper triangular matrix.``#include ``#define N 4``using` `namespace` `std;` `// Function to check matrix is in upper triangular``// form or not.``bool` `isUpperTriangularMatrix(``int` `mat[N][N])``{``    ``for` `(``int` `i = 1; i < N; i++)``        ``for` `(``int` `j = 0; j < i; j++)``            ``if` `(mat[i][j] != 0)``                ``return` `false``;``    ``return` `true``;``}` `// Driver function.``int` `main()``{``    ``int` `mat[N][N] = { { 1, 3, 5, 3 },``                      ``{ 0, 4, 6, 2 },``                      ``{ 0, 0, 2, 5 },``                      ``{ 0, 0, 0, 6 } };``    ``if` `(isUpperTriangularMatrix(mat))``        ``cout << ``"Yes"``;``    ``else``        ``cout << ``"No"``;``    ``return` `0;``}`

## Java

 `// Java Program to check upper``// triangular matrix.``import` `java.util.*;``import` `java.lang.*;` `public` `class` `GfG``{``    ``private` `static` `final` `int` `N = ``4``;` `    ``// Function to check matrix is in``    ``// upper triangular form or not.``    ``public` `static` `Boolean isUpperTriangularMatrix(``int` `mat[][])``    ``{``        ``for` `(``int` `i = ``1``; i < N ; i++)``            ``for` `(``int` `j = ``0``; j < i; j++)``                ``if` `(mat[i][j] != ``0``)``                    ``return` `false``;``        ``return` `true``;``    ``}``    ` `    ``// driver function``    ``public` `static` `void` `main(String argc[]){``        ``int``[][] mat= { { ``1``, ``3``, ``5``, ``3` `},``                       ``{ ``0``, ``4``, ``6``, ``2` `},``                       ``{ ``0``, ``0``, ``2``, ``5` `},``                       ``{ ``0``, ``0``, ``0``, ``6` `} };``                    ` `        ``if` `(isUpperTriangularMatrix(mat))``            ``System.out.println(``"Yes"``);``        ``else``            ``System.out.println(``"No"``);``    ``}``}` `/* This code is contributed by Sagar Shukla */`

## Python3

 `# Python3 Program to check upper``# triangular matrix.` `# Function to check matrix``# is in upper triangular``def` `isuppertriangular(M):``    ``for` `i ``in` `range``(``1``, ``len``(M)):``        ``for` `j ``in` `range``(``0``, i):``            ``if``(M[i][j] !``=` `0``):``                    ``return` `False``    ``return` `True``    ` `# Driver function.``M ``=` `[[``1``,``3``,``5``,``3``],``    ``[``0``,``4``,``6``,``2``],``    ``[``0``,``0``,``2``,``5``],``    ``[``0``,``0``,``0``,``6``]]` `if` `isuppertriangular(M):``    ``print` `(``"Yes"``)``else``:``    ``print` `(``"No"``)` `# This code is contributed by Anurag Rawat`

## C#

 `// C# Program to check upper``// triangular matrix.``using` `System;` `public` `class` `GfG``{``    ``private` `static` `int` `N = 4;` `    ``// Function to check matrix is in``    ``// upper triangular form or not.``    ``public` `static` `bool` `isUpperTriangularMatrix(``int` `[,]mat)``    ``{``        ``for` `(``int` `i = 1; i < N ; i++)``            ``for` `(``int` `j = 0; j < i; j++)``                ``if` `(mat[i, j] != 0)``                    ``return` `false``;``        ``return` `true``;``    ``}``    ` `    ``// Driver function``    ``public` `static` `void` `Main(){``        ``int` `[,]mat= { { 1, 3, 5, 3 },``                    ``{ 0, 4, 6, 2 },``                    ``{ 0, 0, 2, 5 },``                    ``{ 0, 0, 0, 6 } };``                    ` `        ``if` `(isUpperTriangularMatrix(mat))``            ``Console.WriteLine(``"Yes"``);``        ``else``            ``Console.WriteLine(``"No"``);``    ``}``}` `/* This code is contributed by vt_m */`

## PHP

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## Javascript

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Output:

`Yes`

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