What is Identity Matrix

What is Identity Matrix?

The concept of an identity matrix is fundamental in the field of linear algebra and mathematics. An identity matrix, often denoted as ‘I’ or ‘I_n’, is a square matrix with a special set of properties that make it unique and essential in various mathematical and practical applications.

1. Introduction to Identity Matrix

An identity matrix is a square matrix in which all the elements of the principal diagonal are ones, and all other elements are zeros. In simpler terms, it’s a matrix that doesn’t change the value of any vector when multiplied by it. The size of the identity matrix is usually represented as ‘n x n,’ where ‘n’ is the number of rows and columns.

2. Properties of Identity Matrix

Size and Structure

The size of an identity matrix is determined by the number of rows or columns, denoted as ‘n.’ It is always a square matrix, meaning the number of rows is equal to the number of columns. For example, a 3×3 identity matrix would look like this:


One of the fundamental properties of the identity matrix is that when it is multiplied by any square matrix ‘A,’ the result is the same matrix ‘A.’ This property is expressed as ‘I * A = A.’ It acts as the multiplicative identity in matrix multiplication.


In addition, when an identity matrix is added to any matrix ‘A,’ the result is again the same matrix ‘A.’ This property is expressed as ‘A + I = A.’ It acts as the additive identity in matrix addition.

Notation of Identity Matrix

The identity matrix is commonly represented using ‘I’ or ‘I_n,’ where ‘n’ specifies the size of the identity matrix. The subscript ‘n’ is often omitted when the size is evident from the context.

Applications of Identity Matrix

The identity matrix plays a pivotal role in various mathematical and practical applications.

Linear Transformations

In linear algebra, identity matrices are used to describe linear transformations. They serve as a reference point for understanding how other matrices affect vector spaces.

Inverse Operations

Identity matrices are essential in the concept of inverse matrices. When a matrix is multiplied by its inverse, the result is an identity matrix, allowing us to reverse operations.

Eigenvalues and Eigenvectors

Eigenvalues and eigenvectors are crucial in various mathematical and scientific fields. Identity matrices are used to calculate eigenvalues and eigenvectors of other matrices.

Creating Identity Matrix

Square Identity Matrix

Creating a square identity matrix is straightforward. To create an ‘n x n’ identity matrix, you simply fill the principal diagonal with ones and the rest of the matrix with zeros.

Non-Square Identity Matrix

In some cases, you might need a non-square identity matrix, where the number of rows and columns is not equal. This can be achieved by specifying the dimensions and creating the matrix accordingly.

Identity Matrix in Real Life

The concept of identity matrices might seem abstract, but they have practical applications in various fields, including computer graphics, physics, and engineering. They are used in computer graphics to represent transformations, in physics to understand quantum mechanics, and in engineering to solve systems of linear equations.


In conclusion, the identity matrix is a fundamental concept in linear algebra with unique properties. It serves as the cornerstone of matrix operations, playing a vital role in mathematics and various real-world applications.

Frequently Asked Questions (FAQs)

What is the significance of the ones and zeros in an identity matrix?

In an identity matrix, the ones along the principal diagonal represent the scaling factor of 1, while the zeros outside the diagonal ensure that other vector values remain unaffected when multiplied.

FAQ 2: How is the identity matrix used in computer graphics?

In computer graphics, the identity matrix is used to represent the initial position and orientation of objects. It serves as a reference point for applying transformations such as translation, rotation, and scaling.

FAQ 3: Can a non-square identity matrix exist?

Yes, a non-square identity matrix can exist. In such cases, the number of rows and columns is not equal, but the identity properties are maintained for the available dimensions.

FAQ 4: Why are identity matrices important in solving linear equations?

Identity matrices are crucial in solving linear equations because they help determine the unique solutions to systems of equations, making it easier to find unknown variables.

FAQ 5: How are identity matrices related to eigenvalues and eigenvectors?

Identity matrices are used in the calculation of eigenvalues and eigenvectors of other matrices. They play a role in understanding the behavior of linear transformations in different contexts.

Related searches

What is identity matrix with example
What is identity matrix multiplication
What is identity matrix 2×2
How to find identity matrix
Identity matrix of order 3
Identity matrix example 3×3
Square of identity matrix
Value of i in matrix


What is Adultery in Islam

Leave a Comment