# JavaScript: Check whether a given matrix is lower triangular or not

## JavaScript Basic: Exercise-121 with Solution

Write a JavaScript program to check whether a given matrix is lower triangular or not.

Note: A square matrix is called lower triangular if all the entries above the main diagonal are zero.

Sample Solution:

HTML Code:

``````<!DOCTYPE html>
<html>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title> Check whether a given matrix is lower triangular or not</title>
<body>

</body>
</html>
```
```

JavaScript Code:

``````function lower_triangular_matrix(user_matrix) {
for (var i = 0; i < user_matrix.length; i++)
{
for (var j = 0; j < user_matrix[0].length; j++)
{
if (j > i && user_matrix[i][j] !== 0)
return false;
}
}
return true;
}

console.log(lower_triangular_matrix([[1, 0, 0],[2, 0, 0], [0, 3, 3]]));
console.log(lower_triangular_matrix([[1, 0, 1],[2, 0, 0], [0, 3, 3]]));
``````

Sample Output:

```true
false
```

Flowchart:

ES6 Version:

``````function lower_triangular_matrix(user_matrix) {
for (let i = 0; i < user_matrix.length; i++)
{
for (let j = 0; j < user_matrix[0].length; j++)
{
if (j > i && user_matrix[i][j] !== 0)
return false;
}
}
return true;
}

console.log(lower_triangular_matrix([[1, 0, 0],[2, 0, 0], [0, 3, 3]]));
console.log(lower_triangular_matrix([[1, 0, 1],[2, 0, 0], [0, 3, 3]]));
``````

Live Demo:

See the Pen javascript-basic-exercise-121 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.

﻿

## JavaScript: Tips of the Day

Example:

```const parseCookie = str =>
str
.split(';')
.map(v => v.split('='))
.reduce((acc, v) => {
acc[decodeURIComponent(v[0].trim())] = decodeURIComponent(v[1].trim());
return acc;
}, {});
console.log(parseCookie('foo=bar; equation=E%3Dmc%5E2')); // { foo: 'bar', equation: 'E=mc^2' }
```

Output:

```[object Object] {
equation: "E=mc^2",
foo: "bar"
}
```

We are closing our Disqus commenting system for some maintenanace issues. You may write to us at reach[at]yahoo[dot]com or visit us at Facebook