scientific-programming-exercises/ex_42.py

import numpy as np


A = np.array(
	[ [0, 1, 1, 0, 0, 0]
	, [1, 0, 1, 0, 1, 0]
	, [1, 1, 0, 1, 0, 0]
	, [0, 0, 1, 0, 1, 0]
	, [0, 1, 0, 1, 0, 1]
	, [0, 0, 0, 0, 1, 0]
	])

eigvalues, eigvectors = np.linalg.eigh(A)
print(eigvalues)
print(eigvectors)

l_max_i = eigvalues.argmax()
l_max = eigvalues[l_max_i]
print(l_max_i, l_max)
v_max = eigvectors[l_max_i]

def some_norm(M):
	return np.abs(M).max()

B = A
for k in range(1, 21):
	B = B.dot(A)
	print("some kind of error for k =", k, ":", some_norm(B - l_max**k * np.outer(v_max, v_max)) / l_max**k)



print(v_max.argmax())