when to use numpy dot code example

Example 1: numpy.dot

>>> a = [[1, 0], [0, 1]]
>>> b = [[4, 1], [2, 2]]
>>> np.dot(a, b)
array([[4, 1],
       [2, 2]])

Example 2: numpy dot product

a = np.array([1,2,3]) 
b = np.array([4,5,6]) 
np.dot(a,b)
32