JavaScript: Returns n rows by n columns identity matrix

JavaScript Function: Exercise-10 with Solution

Generate Identity Matrix

Write a JavaScript function which returns the n rows by n columns identity matrix.

Pictorial Presentation:

Sample Solution-1:

JavaScript Code:

// Define a function named matrix that prints a square matrix with diagonal elements set to 1 and others to 0
function matrix(n) {
    // Initialize variables i and j for row and column indices
    var i;
    var j;

    // Iterate through each row
    for (i = 0; i < n; i++) {
        // Iterate through each column
        for (j = 0; j < n; j++) {
            // Check if the current position is on the diagonal (i equals j)
            if (i === j) {
                // Print 1 if on the diagonal
                console.log(' 1 ');
            } else {
                // Print 0 if not on the diagonal
                console.log(' 0 ');
            }
        }
        // Print a line of dashes to separate rows
        console.log('----------');
    }
}

// Call the matrix function with the parameter 4
matrix(4); 

Output:

 1 
 0 
 0 
 0 
----------
 0 
 1 
 0 
 0 
----------
 0 
 0 
 1 
 0 
----------
 0 
 0 
 0 
 1 
----------

Flowchart:

Live Demo:

See the Pen JavaScript -Returns n rows by n columns identity matrix-function-ex- 10 by w3resource (@w3resource) on CodePen.

Sample Solution-2:

JavaScript Code:

// Define a function named identity_matrix that generates an identity matrix of size n
function identity_matrix(n) {
  // Initialize an empty array to store the identity matrix
  let imatrix = [];

  // Iterate through each row
  for (let i = 0; i < n; i++) {
    // Initialize an empty array to store the current row
    let row = [];

    // Iterate through each column
    for (let j = 0; j < n; j++) {
      // Check if the current position is on the diagonal (i equals j)
      if (i === j) {
        // If on the diagonal, push 1 to the row
        row.push(1);
      } else {
        // If not on the diagonal, push 0 to the row
        row.push(0);
      }
    }

    // Push the completed row to the identity matrix
    imatrix.push(row);
  }

  // Return the generated identity matrix
  return imatrix;
}

// Log the result of calling identity_matrix with the parameter 4 to the console
console.log(identity_matrix(4)); 

Output:

 [[1,0,0,0],[0,1,0,0],[0,0,1,0],[0,0,0,1]]

Explanation:
The above function first creates an empty matrix array “imatrix“ to hold the identity matrix. It then loops through n times to create n rows and columns. In each row, the array is created empty, and then the loop is repeated n times to create each column. For each column, it checks if the row index i is equal to the column index j. If i and j are equal, it pushes a 1 to the row array, otherwise it pushes a 0. After completing the row, it pushes the row array to the matrix array. Upon creating all rows and columns, the function returns the matrix array representing the identity matrix.

Flowchart:

Live Demo:

See the Pen javascript-function-exercise-10-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that generates an n x n identity matrix using nested loops.
• Write a JavaScript function that creates an identity matrix recursively for a given size n.
• Write a JavaScript function that constructs an identity matrix and then transposes it to verify its properties.
• Write a JavaScript function that returns a two-dimensional array representing the identity matrix without using built-in array methods.

Improve this sample solution and post your code through Disqus.

Previous: Write a JavaScript function which accepts an argument and returns the type.
Next: Write a JavaScript function which will take an array of numbers stored and find the second lowest and second greatest numbers, respectively.