# Calculate the sum of the diagonal elements of a NumPy array in Python 
# importing Numpy package
import numpy as np
  
# creating a 3X3 Numpy matrix
n_array = np.array([[55, 25, 15],
                    [30, 44, 2],
                    [11, 45, 77]])
  
# Displaying the Matrix
print("Numpy Matrix is:")
print(n_array)
  
# calculating the Trace of a matrix
trace = np.trace(n_array)
  
  
print("\nTrace of given 3X3 matrix:")
print(trace)