Matrix multiplication, computation

Summary

• If $A$ is $n×m$ and $B$ is $m×l$ then $C=AB$ is defined and element ${i,j}$ of $C$ is given by the dot product of row $i$ of $A$ with column $j$ of $B$ ,

$$c_{i,j}=a_{i,⋅}⋅b_{⋅,j}$$

• where $i=1,⋯,n$ and $j=1,⋯,l$ .