dot product code example

Example 1: dot product ocaml

let rec safe_dot_product (vect1: int list) (vect2: int list) : int option = 
  match (vect1, vect2) with
    | [],[] -> Some 0
    | [],_ -> None
    | _,[] -> None
    | (x::xs, y::ys) ->
      match safe_dot_product xs ys with
        | None -> None
        | Some m -> Some ((x*y) + m)

Example 2: dot product python

A = [1,2,3,4,5,6]
B = [2,2,2,2,2,2]

# with numpy
import numpy as np
np.dot(A,B) # 42
np.sum(np.multiply(A,B)) # 42
#Python 3.5 has an explicit operator @ for the dot product
np.array(A)@np.array(B)# 42
# without numpy
sum([A[i]*B[i] for i in range(len(B))]) # 42

Example 3: dot product

Let a be a vector with coordinates (a1, a2, a3)
Let b be a vector with coordinates (b1, b2, b3)

Dot Product: 
<a1, a2, a3> • <b1, b2, b3> = a1*b1 + a2*b2 + a3*b3

a • b = |a||b|cosθ, where θ is the angle between the two vectors

Example 4: numpy dot product

a = np.array([[1,2],[3,4]]) 
b = np.array([[11,12],[13,14]]) 
np.dot(a,b)
[[37  40], [85  92]]

Example 5: dot product array

import numpy.matlib 
import numpy as np 

a = np.array([[1,2],[3,4]]) 
b = np.array([[11,12],[13,14]]) 
np.dot(a,b)

Example 6: r dot product

a = c(1,2)
b = c(0,1)

# Perform the dot product
a%*%b