Вычисления значения функции y(x) для всех различных вариантов входных параметров

#include <iostream>
#include <cmath>
using namespace std;
 
double y (double x, double a, double b, double c)
{
    double exp;
 
    if (exp(pow(a+b)))<(exp(x)) return cos(sqrt(fabs(x+abc)));
    else if (exp(pow(a+b)))>(exp(x)) return sin() +(x*x);
    return atan(abc)+cbrt(x); 
}
 
int main()
{
    double x;
 
    cout << "x="; cin >> x;
 
    cout << "if a=4.2,     b=5.3,   c=1.5   y(" << x << ")=" << y(x,4.2,5.3,1.5) << "\n";
    cout << "if a=-0.35,   b=1.8,   c=-1.8  y(" << x << ")=" << y(x,-0.35,1.8,-1.8) << "\n";
    cout << "if a=2.8,     b=-0.6,  c=2.0   y(" << x << ")=" << y(x,2.8,-0.6,2.0) << "\n";
 
return 0;
}

double y(double x, double a, double b, double c)
{
    if (x < a)
        return; ////////sin*....
    if (a <= x <= b * b)
        return; ////ln|x|*...
    if (x > b * b)
        return;/////////e^(2,5x).......
}

#include <iostream>
#include <cmath>
double y(double x, double a, double b, double z)
{
    if (x < a)
        return 2.8 * pow(sin(a * x), 2) - b * x * x * x * z;
    else if (x <= b * b)
        return z * cos(pow(a * x + b, 2)) + log(z);
    else
        return exp(2.5 * a * x) + z * a * b * x;
}
int main()
{
    double x;
    std::cout << "x = "; std::cin >> x;
 
    double a = -5.0;
    double b = 2.5;
    double z = log(b * x * x * x);
    std::cout << "If a = " << a << ", "
        << "b = " << b << ", "
        << "z = ln|bx^3| then y = " << y(x, a, b, z) << std::endl;
 
    a = 3.0;
    b = 5.0;
    z = log(b * x);
    std::cout << "If a = " << a << ", "
        << "b = " << b << ", "
        << "z = ln|bx| then y = " << y(x, a, b, z) << std::endl;
 
    a = -10.0;
    b = 3.0;
    z = log(b * x * x);
    std::cout << "If a = " << a << ", "
        << "b = " << b << ", "
        << "z = ln|bx^2| then y = " << y(x, a, b, z) << std::endl;
 
    return 0;
}