# -*- coding: utf-8 -*-
import numpy as np

A = np.array([[4,-1,1],
              [-1,4,-2],
              [1,-2,4]],float)

b = np.array([12,-1,5],float)

emax=10**-13
N=100
n=3
x=np.zeros(n)

for k in range(N):
    x_new=x.copy()
    x[0]=(12+x[1]-x[2])/4
    x[1]=(-1+x[0]+2*x[2])/4
    x[2]=(5-x[0]+2*x[1])/4
    
    e=np.linalg.norm(x_new-x)
    if e<emax:
        break
    print(k,x)