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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>
<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:

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

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.


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

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JavaScript: Tips of the Day

Returns the sum of the powers of all the numbers from start to end (both inclusive)

Example:

const sumPower = (end, power = 2, start = 1) =>
  Array(end + 1 - start)
    .fill(0)
    .map((x, i) => (i + start) ** power)
    .reduce((a, b) => a + b, 0);
console.log(sumPower(10)); // 385
console.log(sumPower(10, 3)); // 3025
console.log(sumPower(10, 3, 5)); // 2925 

Output:

385
3025
2925