C++ - Никита - 3

#include <iostream>
#include <cmath>

using namespace std;

double factorial(double num){
    if(num < 0)
        return 0;
    if (num == 0)
        return 1;
    else
        return num * factorial(num - 1);
}
double Calc(double x, double epsilon) {
    double res, a;
    a = x;
    res = a;
    int i = 1;
    do {
        a = a*(-1*(pow(x,2)*factorial(2*i+1))/factorial(2*i+3));
        res += a;
        i++;
    } while (abs(a) >= epsilon);
    return res;
}

int main()
{
    double x, e, n;
    cin >> x >> e;
    n = Calc(x,e);
    cout << n;
    return 0;
}