XV

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <math.h>
#include <stdlib.h>
using namespace std;

int main() {
freopen("input.txt", "r", stdin);
    int i, j, n, m;
    //создаем массив
    cout << "Number of equations: ";
    cin >> n;
    cout << "Number of variables: ";
    cin >> m;
    m += 1;
    double matrix[3][4];

    double e;
    cout << "E: ";
    cin >> e;
    //инициализируем
    for (i = 0; i < n; i++) {
        for (j = 0; j < m; j++) {
            cout << " Element " << "[" << i + 1 << ", " << j + 1 << "]: ";
            cin >> matrix[i][j];
        }
    }
    //выводим массив
    cout << "matrix: " << endl;
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < m; j++)
            cout << matrix[i][j] << " ";
        cout << endl;
    }
    cout << endl;
    //Метод простых итераций
    int iteratoin = 0;
    double tmpOpenX, openX = NULL;
    double answer[3] = {0, 0, 0};
    double tmpAnswer[3] = {0, 0, 0,};
    for (i = 0; i < n; i++) {
        double tmp = matrix[i][i];
        for (j = 0; j < m; j++) {
            matrix[i][j] /= (3!=j)? -tmp : tmp;
            cout << matrix[i][j] << " ";
        }
        cout << endl;
    }
    for (i = 0; i < n; i++) {
        answer[i] = matrix[i][3];
    }
m1:
    for (i = 0; i < n; i++) {
        for (j = 0; j < m; j++) {
            if (j == i) {
                continue;
            }
            tmpAnswer[i] += matrix[i][j] * (j!=3)?answer[j]:1;
        }
        cout << tmpAnswer[i] << " ";
    }
    cout << endl;
    memcpy(answer, tmpAnswer, sizeof(double)*n + 1);
    tmpAnswer[0] = tmpAnswer[1] = tmpAnswer[2] = 0;
    tmpOpenX = max(fabs(answer[0]),max(fabs(answer[1]), fabs(answer[2])));
    if (!openX) {
        openX = tmpOpenX;
    } else if(e > tmpOpenX - openX){
        goto m2;
    }
    goto m1;

m2:
    //Выводим решения
    for (i = 0; i < n; i++)
        cout << answer[i] << " ";
    cout << endl;

    system("pause");
    return 0;
}