power.py

import  numpy as np

A = np.array([[1,2],[4,3]])
x0 = np.array([[1],[0]])

def iterate(A,x):
    rho = np.dot(A,x)
    nk = np.max(np.absolute(rho))
    xk = 1/nk* rho
    
    return rho, nk, xk

rho, nk, xk = iterate(A,x0)