Confused in Vectorization

Hi! I still confused about the vectorization.
When we write the input, we write it like
a = [x1, x2, x3] as a numpy array. Isn’t it already a vector?

Yes A is a list, and can be used as a matrix or vector, a numpy type is such that corresponds to the nupmy library which has been optimized for matrix operations.

“vectorization” typically refers not to the data format, but to the methods used in calculations with that data.

Vectorization would use matrix math operators (like dot products) instead of using a for-loop to iterate through the individual data elements.