method upper relaxation

from math import *

global eps
global n


def mistake(xk, xkp):                                #stopping criterion
    norm = 0
    for i in range(n):
        norm += (xk[i] - xkp[i])*(xk[i] - xkp[i])
    return (sqrt(norm) < eps)


eps = 0.0000001

print("input matrix range")
n = int(input())
print("if you want input from keyboard, press 1,\nif you want to use formula press 2,\nif you want input from file press 3.")
inp = int(input())
print("input iterative parametr")
u = float(input())


transp = [[0 for j in range(n)] for i in range(n)]
mult = [[0 for j in range(n)] for i in range(n)]
answ = [0 for i in range(n)]
prev = [0 for i in range(n)]
ans_col = [0 for i in range(n)]
mult_ans = [0 for i in range(n)]

matrix = [[0 for j in range(n)] for i in range(n)]

if (inp == 1):                                                #from terminal
    for i in range(n):
        print("input", i + 1, "line")
        line = list(map(float, input().split()))
        for j in range(n):
            matrix[i][j] = line[j]
            transp[j][i] = matrix[i][j]
        ans_col[i] = line[n]


elif inp == 2:                                                #using formula
    for i in range(n):
        for j in range(n):
            if (i != j):
                matrix[i][j] = (i + j) / 65
            else:
                matrix[i][j] = 275 + j / 15 + i / 50
            transp[j][i] = matrix[j][i]
        ans_col[i] = 750 - (i * i * i)

elif inp == 3:                                                 #from file named 'input.txt'
    fin = open('input.txt', 'r')
    for i in range(n):
        line = list(map(float, (fin.readline()).split()))
        for j in range(n):
            matrix[i][j] = line[j]
            transp[j][i] = matrix[i][j]
        ans_col[i] = line[n]
    fin.close()


for i in range(n):                                             #multiplied matrix
    for j in range(n):
        mult[i][j] = 0
        for k in range(n):
            mult[i][j] += transp[i][k] * matrix[k][j]

for i in range(n):                                             #multiplied answers
    mult_ans[i] = 0
    for k in range(n):
        mult_ans[i] += transp[i][k] * ans_col[k]

for i in range(n):
    answ[i] = 0

count = 1
for i in range(n):                                           #using method of upper relexation
    prev[i] = answ[i]
for i in range(n):
    summa = 0
    for j in range(i):
        summa += (mult[i][j] * answ[j])
    for j in range(i, n):
        summa += (mult[i][j] * prev[j])
    answ[i] = u * (mult_ans[i] - summa) / mult[i][i] + prev[i]


while (not mistake(answ, prev)):
    count += 1
    for i in range(n):
        prev[i] = answ[i]
    for i in range(n):
        summa = 0
        for j in range(i):
            summa += (mult[i][j] * answ[j])
        for j in range(i, n):
            summa += (mult[i][j] * prev[j])
        answ[i] = u * (mult_ans[i] - summa) / mult[i][i] + prev[i]


for i in range(n):
    print("answ[" + str(i + 1) + "] = " + str(answ[i]))

print("\nIT =", count)