# Write a NumPy program to convert angles from radians to degrees for all elements in a given array.  
 import numpy as np
x = np.array([-np.pi, -np.pi/2, np.pi/2, np.pi])
r1 = np.degrees(x)
r2 = np.rad2deg(x)
assert np.array_equiv(r1, r2)
print(r1)
