Vector Outer Product
Assume that a and b are vectors. Then, the outer product of a and b is C.
ab'= C
where
a is a column vector, having m elements,
b is a column vector, having n elements,
b' is the transpose of b, which makes b' a row vector, and
C is a rectangular m x n matrix
Unlike the inner product, the outer product of two vectors produces a rectangular matrix, not a scalar. This is illustrated below.
a =
v
w
b =
x
y
z
Then,
C = ab' =
v * x v * y v * z
w * x w * y w * z
Notice that the elements of Matrix C consist of the product of elements from Vector A crossed with elements from Vector B. Thus, Matrix C winds up being a matrix of cross products from the two vectors.