NameError name np is not defined

This error message indicates that the variable or function 'np' has not been defined in the current context.

In most cases, 'np' is an alias or shorthand for the popular numerical computing library NumPy. To resolve this error, you need to import NumPy at the beginning of your code using the following line:

import numpy as np

This will create an alias 'np' that you can use to call NumPy functions throughout your code.