#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
double function_1(double t, double x, double y) { return (3*x+4*y) ; }
double function_2(double t, double x, double y) { return (2*x+y); }
double y_n = 1;
double x_n = -1;
double t_n = 0;
double t_k = 1000;
double n = 5000, h = 0.01;
int main()
{
    string path = "E:\\university\\Math\\laba3\\laba3.txt";
    ofstream file(path);
    double k1 = 0, k2 = 0, k3 = 0, k4 = 0;
    double l1 = 0, l2 = 0, l3 = 0, l4 = 0;
    double y = y_n;
    double x = x_n;
    file << t_n <<'\t' << x << '\t' << y << '\n';
    for (double i = t_n + h; i <= t_k; i += h)
    {
        k1 = function_1(i, x, y);
        l1 = function_2(i, x, y);
        k2 = function_1(i + (h / 2.0), x + ((h / 2.0)*k1), y + ((h / 2.0)*l1));
        l2 = function_2(i + (h / 2.0), x + ((h / 2.0)*k1), y + ((h / 2.0)*l1));
        k3 = function_1(i + (h / 2.0), x + ((h / 2.0)*k2), y + ((h / 2.0)*l2));
        l3 = function_2(i + (h / 2.0), x + ((h / 2.0)*k2), y + ((h / 2.0)*l2));
        k4 = function_1(i + h, x + h*k3, y + h*l3);
        l4 = function_2(i + h, x + h*k3, y + h*l3);
        x = x + (h / 6.0)*(k1 + 2.0*k2 + 2.0*k3 + k4);
        y = y + (h / 6.0)*(l1 + 2.0*l2 + 2.0*l3 + l4);
        file << i << '\t'<< x << '\t' << y << '\n';
    }
    file.close();
    //system("notepad file.txt");
    return 0;
}