Outer Product

See Dyadic products explanation at the bottom of Continuum Mechanics

$$\left[\begin{array}{ccc}{a}_1{b}_1& \dots & a_1{b}_m\\ ⋮& \ddots & ⋮\\ a_n{b}_1& \dots & a_n{b}_m\end{array}\right]$$

$c_{ij}=a_i{b}_j$