taniej już chyba nie będzie

#include <iostream>
#include <fstream>
#define _USE_MATH_DEFINES
#include <cmath>
#include <stack>
#define M_PI_2     1.57079632679489661923
using namespace std;

int sgn(long double x){
    if(x>0)
        return 1;
    else
        return -1;
}
void licz_double(long double x, long double epsilon){
    long double suma = x;
    stack<long double> stos_sum;
    if(x <= 1 && x >= (-1)){
        suma = x;
        stos_sum.push(suma);
        long double potega = x;
        long double nastepny = 1000.0;
        bool p=0;
        for(int n = 1; nastepny > epsilon; n+=1){
            potega = potega * x * x;
            if(p==1){
                suma = suma + (potega/(2*n + 1.0));
                stos_sum.push(potega/(2*n + 1.0));
            }
            else{
                suma = suma - (potega/(2*n + 1.0));
                stos_sum.push(-potega/(2*n + 1.0));
            }
            p = !p;
            nastepny = abs((potega*x*x)/(2*(n+1) + 1.0));
        }
    }
    else{
        suma = (sgn(x) * M_PI_2) - (1/x);
        long double potega = x;
        bool p = 1;
        stos_sum.push(suma);
        long double nastepny = 1000.0;
        for(int n =1; nastepny >= epsilon; n+=1){
            potega = potega * x *x;
            if(p==1){
                suma = suma + 1/((2*n + 1)*potega);
                stos_sum.push(1/((2*n + 1)*potega));
            }
            else{
                suma = suma - 1/((2*n + 1)*potega);
                stos_sum.push(-1/((2*n + 1)*potega));
            }
            p = !p;
            nastepny = abs(1/((2*n + 3)*(potega*x*x)));
        }
    }
        long double arctan = atan(x);
        long double wynik =0.0;
        int size = stos_sum.size();
        for(int i=0; i <size; i++){
            wynik = wynik + stos_sum.top();
            stos_sum.pop();
        }
        cout << "wynik obliczen:\t"<< wynik << "\n";
        cout << "blad wzgledny:\t" << (wynik-arctan)/arctan << "\n";
}
int main(){
    cout << fixed;
    long double x=0;
    long double epsilon=0;
    cout.precision(30);

    cout << "arctg z zadana dokladnoscia\n";
    cout << "podaj argument funkcji\n";
    cin >> x;
    cout << "podaj zadana dokladnosc\n";
    cin >> epsilon;

    licz_double(x, epsilon);
    return 0;
}