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

Last update on May 30 2022 09:59:00 (UTC/GMT +8 hours)

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

Previous: Write a JavaScript program to check whether a point lies strictly inside a given circle.
Next: Write a JavaScript program to check whether a given array of integers represents either a strictly increasing or a strictly decreasing sequence.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04