Dot product

• $a\cdot b=a^{T}b={\sum }_{d=1}^D{a}_d{b}_d$
• $a\cdot b=a_1{b}_1+a_2{b}_2+a_3{b}_3$
• Takes 2 vectors, multiplies them element wise, then add those products together
• Both input vectors must have the same shape