Vector Dot-Product in Microsoft Excel

Dot-product, or rather vector dot-product, does not have a familiar phrase to use in Microsoft Excel. For instance, if you want to perform the following operation,

=(A1*B1)+(A2*B2)+(A3*B3)+...+(AK*BK)

which exactly resembles that of a vector dot-product; that is, A*B where A = [A₁ A₂ ... A_K] and B = [B₁ B₂ ... A_K]^T.

(Quick way to obtain the dot-product in Excel...)

Here is the quick way to do that in Microsoft Excel.

For the similar expression above, simply use the built-in function, SUMPRODUCT(). For example,

=SUMPRODUCT(A1:AK,B1:BK)

And the resulting vector dot-product is easily calculated with Microsoft Excel.