Дважды вычислить значение выражения, используя функции возвращающие void и не void

#include <iostream>
#include <cmath>
 
#define x1 (x * x)
#define x2 (x1 * x)
#define x3 (x2 * x)
#define x4 (x3 * x)
#define x5 (x4 * x)
#define x6 (x5 * x)
#define pi 3.1415926535
 
void S(const double x, double &res)
{
    res = ((sin(x1+pi/4)+cos(x2+pi/4))/(sin(x3+pi/3)+cos(x4+pi/3)))*sqrt(abs(sin(x5+(2*pi)/5+cos(x6+(2*pi)/5))));
}
 
double S(const double x)
{
    return ((sin(x1+pi/4)+cos(x2+pi/4))/(sin(x3+pi/3)+cos(x4+pi/3)))*sqrt(abs(sin(x5+(2*pi)/5+cos(x6+(2*pi)/5))));
}
 
int main()
{
    double x = 0.1, res1 = S(x), res2;
    S(x, res2);
    std::cout << res1 << std::endl << res2;
}

#include <iostream>
#include <cmath>
using namespace std;
void proc(int s, int x1, int x2, int x3, int x4, int x5, int x6)
{
    float chislitel = (sin(x1 + (M_PI / 4)) + cos(x2 + (M_PI / 4)));
    float znamenatel = (sin(x3 + (M_PI / 3)) + cos(x4 + (M_PI / 3)));
    float res = sqrt(abs(sin(x5 + (2 * (M_PI)) / 5) + cos(x6 + (2 * (M_PI)) / 5)));
    float rez = (chislitel / znamenatel) * res;
    cout << "\n proc=" << rez;
}
float fun(float x1, float x2)
{
    float chislitel = (sin(x1 + (M_PI / 4)) + cos(x2 + (M_PI / 4)));
 
    return chislitel;
}
 
int main()
{
    float s, x1, x2, x3, x4, x5, x6;
    cout << "\n Vvod x1,x2,x3,x4,x5,x6";
    cin >> x1 >> x2 >> x3 >> x4 >> x5 >> x6;
    s = ((fun(x1, x2)) / (fun(x3, x4))) * sqrt(abs(fun(x5, x6)));
    cout << "\n s=" << s;
    proc(s, x1, x2, x3, x4, x5, x6);
}