AttributeError: 'numpy.ndarray' object has no attribute 'sin'?

Question

Below is my short code, but it has an error: "AttributeError: 'numpy.ndarray' object has no attribute 'sin'" . I don't understand why and how to fix. Please guide me!

Thanks a lot in advance!

import numpy as np
w1 = 0.3
w2 = 0.2
w0 = 0.4

x1 = np.linspace(0, 10, 50)
x2 = np.linspace(0, 10, 50)
X, Y = np.meshgrid(x1, x2)

A = np.array([1,X,Y],dtype=object)
w = np.array([[w0],[w1],[w2]])
Z = np.sin(A.dot(w))
print (Z)

Answer 1

Because you define A with dtype=object , the result of A.dot(w) will be of type object as well. As a consequence of this, numpy.sin tries to call sin as a member function of the elements in the result of A.dot(w) which is not defined.

Produces error: np.sin(np.array([np.array(1)], dtype=object))
No error: np.sin(np.array([np.array(1)]))

As @Adelin has mentioned above, simply call np.sin(A.dot(w)[0] .