Identity Matrix
Square matrix in which all the elements on the main diagonal are 1 and all the other elements are 0.
Example
The 4 × 4 identity matrix is :I = [latex]\begin{pmatrix}1 & 0 & 0 & 0\\0 & 1 & 0 & 0\\0 & 0 & 1 & 0\\ 0 & 0 & 0 & 1\end{pmatrix}[/latex]