Программа обработки структур

#include <iostream>
#include <conio.h>
#include <cmath>
#include <windows.h>
#include <stdlib.h>
double PI = 3.141592654;
using namespace std;
struct complex {
double real;
double image; };
struct complex sum (struct complex x, struct complex y);
struct complex sub (struct complex x, struct complex y);
struct complex mul (struct complex x, struct complex y);
struct complex div (struct complex x, struct complex y);
double abs (struct complex x);
double arg (struct complex x);
 
int main(void)
{
complex a,
    y,
    numerator,
    denominator,
    temp_1, temp_2;
 
    cout<< "Vvedite deystvitelnuyu chast kompleksnogo chisla: ";
    cin >> a.image; cout << endl;
    temp_1.real = 3; temp_1.image = 0;
    temp_2.real = 0; temp_2.image = 1;
    numerator = mul(sum(a, temp_1), sub(a, temp_2));
    temp_1.real = 2; temp_1.image = 0;
    temp_2.real = 0; temp_2.image = 3;
    denominator = mul(sum(mul(temp_1), a),mul(temp_2, a)),
                      sum(a, temp_1);
    if (denominator.real == 0 && denominator.image == 0)
    {
    cout << "Nedopust. znachenie v znamenatele, programma zavershena"<<endl;
    return 0;
    }
    y = div(numerator, denominator);
    cout <<"Znachenie modulya functsii: "<<abs(y) <<endl;
    cout <<"Znachenie argumenta dunctsii: "<<arg(y) << endl;
    getch(); return 1;
    }
    struct complex sum (struct complex x, struct complex y)
    {
    complex result;
    result.real = x.real + y.real;
    result.image = x.image + y.image;
    return result;
    }
    struct complex sub(struct complex x, struct complex y)
    {
    complex result;
    result.real = x.real - y.real;
    result.image = x.image - y.image;
    return result;
    }
    struct complex mul (struct complex x, struct complex y)
    {
    complex result;
    result.real = x.real*y.real - x.image*y.image;
    result.image = x.real*y.image + x.image*y.real;
    return result;
    }
    struct complex div(struct complex x, struct complex y)
    {
    complex result;
    result.real = (x.real*y.real + x.image*y.image)
            / (y.real*y.real + y.image*y.image);
    result.image = (x.image*y.real - x.real*y.image)
            / (y.real*y.real + y.image*y.image);
            return result;
    }
    double abs(struct complex x)
    {
        double result;
        result = atan2(x.image, x.real);
        result = result/PI * 180;
        return result;
    }

denominator = mul( sum( mul(temp_1, a), temp_2 ), sum(a, temp_1) );

double arg(struct complex x)
{
    return atan2(x.image, x.real);
}