Look at implementation

lookAt.py

import math
import numpy as np

def length(v):
    return math.sqrt((v[0]*v[0])+ (v[1]*v[1]) + (v[2]*v[2]))

def normalize(v):
    l = length(v)
    if l != 0:
        inv = 1.0 / l
        return [v[0] * inv, v[1] * inv, v[2] * inv]
    
    return [0, 0, 0]

def lookAtRH(eye, target, up):
    zaxis = normalize(np.subtract(eye, target)) # The "forward" vector
    xaxis = normalize(np.cross(up, zaxis)) # The "right" vector
    yaxis = np.cross(zaxis, xaxis) # The "up" vector

    orientation = np.array([
        [xaxis[0], yaxis[0], zaxis[0], 0],
        [xaxis[1], yaxis[1], zaxis[1], 0],
        [xaxis[2], yaxis[2], zaxis[2], 0],
        [0, 0, 0, 1],
    ])
    translation = np.array([
        [1, 0, 0, 0],
        [0, 1, 0, 0],
        [0, 0, 1, 0],
        [-eye[0], -eye[1], -eye[2], 1]
    ])

    return np.matmul(translation, orientation