'''
Calculating eigenvalues of state space model with Python Control Package
Finn Aakre Haugen (finn.haugen@usn.no)
Updated 2023 01 10
'''

#%% Imports

import numpy as np
import control

#%% Model parameters

m = 20  # [kg] 
d = 4  # [N/(m/s)] 
k = 2  # [N/m] 

#%% System matrices as 2D arrays

A = np.array([[0, 1], [-k/m, -d/m]])
B = np.array([[0], [1/m]])
C = np.array([[1, 0]])
D = np.array([[0]])

#%% Creating and displaying the state space model

S = control.ss(A, B, C, D)
print('State space model:\n\n', S)

#%% Eigenvalues of S
  
eigval_eigvec_S = np.linalg.eig(A)
eigval_S = eigval_eigvec_S[0]
print (f'Eigenvalues of S: {np.around(eigval_S, decimals=3)}')