JavaScript: Check whether a matrix is a diagonal matrix or not

Last update on May 30 2022 10:00:58 (UTC/GMT +8 hours)

JavaScript Basic: Exercise-115 with Solution

Write a JavaScript program to check whether a matrix is a diagonal matrix or not. In linear algebra, a diagonal matrix is a matrix in which the entries outside the main diagonal are all zero (the diagonal from the upper left to the lower right).

Example:
[1, 0, 0], [0, 2, 0], [0, 0, 3] ]) = true
[1, 0, 0], [0, 2, 3], [0, 0, 3] ]) = false

Pictorial Presentation:

JavaScript: Check whether a matrix is a diagonal matrix or not.

Sample Solution:

HTML Code:

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

</body>
</html>

JavaScript Code:

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


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

Sample Output:

true
false

Flowchart:

ES6 Version:

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


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

Live Demo:

See the Pen javascript-basic-exercise-115 by w3resource (@w3resource) on CodePen.

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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