Python's Numpy dot function returning incorrect value, why?

Real simple, my code is:

import numpy as np


a = np.array([0.4, 0.3])
b = np.array([-0.15, 0.2])

print(np.dot(a,b))

The dot product of this should be 0, and instead i get:

3.3306690738754695e-18

>Solution :

For something like that i’d suggest just using the rounding function to however many decimals you got, or using this:

dotproduct=0
for a,b in zip(a,b):
    dotproduct = dotproduct+a*b
print('Dot product is:', dotproduct)

Which does the dot product regardless of floats or integers.