What is an Identity matrix.

Identity Matrix is a square matrix in which the elements in the diagonal are all 1 and rest are all zeros. It is also called as a Unit Matrix or Elementary matrix. It is represented as $I_n$ or just by $I$, where n represents the size of the square matrix.

An Example of Identity matrix :

$I_1$ = $1$

$I_2$ = $\left[ \begin{matrix}

1 & \phantom{-} 0 \\

0 & \phantom{-} 1 \\

\end{matrix} \right]$


$I_3$ = $\left[ \begin{matrix}

1 & \phantom{-} 0 & \phantom{-} 0 \\

0 & \phantom{-} 1 & \phantom{-} 0 \\

0 & \phantom{-} 0 & \phantom{-} 1 \\

\end{matrix} \right]$