A#1

#include "stdafx.h"
#include <iostream>
#define _USE_MATH_DEFINES
#include "math.h"
#include <windows.h>

using namespace std;

int fact(int n) {
    switch (n) {
    case 0: return 1;
    case 1: return 1;
    default: {
        int k = 1;
        for (int i = 1; i <= n; i++)
            k *= i;
        return k;
    }
    }
}

double receq(double x, double f, double fk, double e, double xi, int i) {
    double t = xi * pow(x, 4) * (4 * i - 2 - x) * fact(4 * i - 6) / ((4 * i - 6 - x) * fact(4 * i - 2));
    f += t;
    if (abs(f - fk)) {
        return f;
    }
    else {
        return receq(x, f, fk, e, t, i + 1);
    }
}

void main()
{
    SetConsoleCP(1251);
    SetConsoleOutputCP(1251);
    setlocale(LC_ALL, "rus");
    double e;
    cout << "Введите точность вычисления" << endl;
    cin >> e;
    double x;
    cout << "Введите x" << endl;
    cin >> x;
    double k, t;
    k = (sin(x) + cos(x) - exp(-x)) / 2.0;
    double r;
    r = receq(x, x*(2 - x) / 2.0, k, e, x*(2 - x) / 2.0, 2);
    cout.precision(15);
    cout << "k = " << k << endl;
    cout << "r = " << r << endl;
    cin >> r;

}