07 - Types of Matrices

Zero Matrix $0_{mn}=(0_{ij})$ ($m\times n$)

Entry $0_{ij}=0$ for $1\le i\le m,1\le j\le n$

Usually $0_{mn}$ is just represented as $0$

Identity matrix $I_n$ ($n\times n$)

$(i,j)$th entry of $I={\delta }_{ij}$
where ${\delta }_{ij}$ is the Kronecker Delta

Usually $I_n$ is just represented as $I$ and it’s just ones on the main diagonal