Степенной метод

#include <iostream>
#include <string>
#include <vector>
#include <cmath>
using namespace std;

void multiplyingMatrix(vector<vector<double>> x, vector <double> &y, vector <double> &l)
{
    int sz = y.size();
    vector <double> yy(sz);
    for (int i = 0; i < sz; ++i)
    {
        double perem = 0;
        for (int j = 0; j < sz; ++j)
        {
            perem += x[i][j] * y[j];
        }
        yy[i] = perem;
       // cout << yy[i] << '\n';
    }
    for (int i = 0; i < sz; ++i)
    {
        l[i] = yy[i] / y[i];
        y[i] = yy[i];
    }
}

int main()
{
    int n;
    cin >> n;
    vector<vector <double>> v(n, vector<double>(n));
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
            cin >> v[i][j];
    }
    vector <double> y(n, 1), lambda(n, 1), lambda2(n, 1);

    vector <double> yy(n, 1);

    /*multiplyingMatrix(v, yy, lambda2);
    for (int i = 0; i < n; ++i)
    {
        cout << lambda2[i] << ' ';
    }*/
    while (true)
    {
        bool f = 0;
        multiplyingMatrix(v, yy, lambda2);
        for (int i = 0; i < n; ++i)
            if (abs(lambda2[i] - lambda[i]) < 0.0001)
            {
                f = 1;
                break;
            }
        if (f)
            break;
        for (int i = 0; i < n; ++i)
        {
            cout << lambda2[i] << ' ';
        }
        cout << '\n';
        for (int i = 0; i < n; ++i)
            lambda[i] = lambda2[i];
    }
    cout << "ANSWER: ";
    for (int i = 0; i < n; ++i)
    {
        cout << lambda2[i] << ' ';
    }

    return 0;
}
/*
4
1.2 0.5 2 1
0.5 1 0.8 2
2 0.8 1 1
1 2 1 2
*/