JavaScript: Check whether a given matrix is an identity matrix

Last update on May 30 2022 09:58:38 (UTC/GMT +8 hours)

JavaScript Basic: Exercise-117 with Solution

Write a JavaScript program to check whether a given matrix is an identity matrix.

Note: In linear algebra, the identity matrix, or sometimes ambiguously called a unit matrix, of size n is the n × n square matrix with ones on the main diagonal and zeros elsewhere.
[[1, 0, 0], [0, 1, 0], [0, 0, 1]] -> true
[[1, 0, 0], [0, 1, 0], [1, 0, 1]] -> false

Pictorial Presentation:

JavaScript: Check whether a given matrix is an identity matrix.

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title> Check if a given matrix is an identity matrix</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function is_identity_Matrix(matrix_data) {
//Checks whether given matrix is a square matrix or not
for (var i = 0; i < matrix_data.length; i++)
  {
    rows = matrix_data.length;
cols = matrix_data[i].length;
if(rows != cols)
  {
   console.log("Matrix should be a square matrix");
   return false;
  }
  }
  for (var i = 0; i < matrix_data.length; i++)
   {
    for (var j = 0; j < matrix_data.length; j++)
     {
      if (matrix_data[i][j] !== 1 && i === j || matrix_data[i][j] && i !== j)
      {
        return false;
      }
    }
  }
  return true;
}
console.log(is_identity_Matrix([[1, 0, 0, 2], [0, 1, 0], [0, 0, 1]]))
console.log(is_identity_Matrix([[1, 0, 0],  [0, 1, 0],  [0, 0, 1]]))
console.log(is_identity_Matrix([[1, 0, 1],  [0, 1, 0],  [0, 0, 1]]))

Sample Output:

Matrix should be a square matrix
false
true
false

Flowchart:

ES6 Version:

function is_identity_Matrix(matrix_data) {
  for (let i = 0; i < matrix_data.length; i++) 
   {
    for (let j = 0; j < matrix_data.length; j++)
     {
      if (matrix_data[i][j] !== 1 && i === j || matrix_data[i][j] && i !== j)
      {
        return false;
      }
    }
  }
  return true;
}

console.log(is_identity_Matrix([[1, 0, 0],  [0, 1, 0],  [0, 0, 1]]))
console.log(is_identity_Matrix([[1, 0, 1],  [0, 1, 0],  [0, 0, 1]]))

Live Demo:

See the Pen javascript-basic-exercise-117 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