nullmátrix
0 m × n = ( 0 0 … 0 0 0 … 0 ⋮ ⋮ ⋱ ⋮ 0 0 … 0 ) {\displaystyle 0_{m\times n}=\left({\begin{array}{cccc}{0}&{0}&{\ldots }&{0}\\{0}&{0}&{\ldots }&{0}\\{\vdots }&{\vdots }&{\ddots }&{\vdots }\\{0}&{0}&{\ldots }&{0}\end{array}}\right)}
