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

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:

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

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

Parse an HTTP Cookie header string and return an object of all cookie name-value pairs

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"
}

 

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