#define _USE_MATH_DEFINES
#include <iostream>
#include <iomanip>
#include <cmath>
#include <math.h>
using namespace std;

int main() {

    1

 double val , x;
     cout << "Number: ";
    cin >> val;
        if (val <= 0)
             {
            printf("sine of %f is %f\n", val, sin (val));
        }
        else if (0  < val && val <= M_PI_4)
                 {
                    printf("arc tangent of %f is %f\n", val, atan(val));
                }
        else if ( M_PI_4 < val && val <= 32)
            {
                x = log2 (val);
                printf ("log2 (%f) = %f.\n", val, x );
            }
    else
    {
        fmod(val,1);
        cout << "Your number is: "  << val << endl;
    }
    cin.get();

    2

    double val;

    cout << "Number: ";
    cin >> val;
    if (val < -1*M_PI)
    {
        printf("ln|x| of %f is %f\n", val, log(abs(val)));
    }
    else if (-1*M_PI  <=  val && val <= M_PI)
    {
        printf("sinx + cos2x is %f is %f\n", val, sin (val) + cos(2*val));
    }
    else if ( M_PI <= val && val < 10)
    {
        printf ("x power 3 + 1 is (%f) = %f.\n", val, pow(val,3) + 1);
    }
    else if ( 10 <= val && val < 100)
    {
        printf ("(x+1) / (x2 + 8) is  (%f) = %f.\n", val, (val + 1) / (pow (val,2) + 8));
    }
    else
    {
        printf ("ln x is  (%f) = %f.\n", val, log(val));
        cout << "Your number is: "  << val << endl;
    }

    cin.get();

    3

    double val, gr, spec;

    cout << "Number Nr. 1 (x)  : ";
    cin >> val;
    cout << "Number Nr. 2 (y)  : ";
    cin >> gr;
    if (val < -10 && gr < -5)
    {
        printf("1/x + 1/y (%f) = %f.\n", val , 1/val + 1/gr );
    }
    else if (-10<= val && val < 0 && -5 <= gr  && gr < 0)
    {
        printf("(x-y) / (x+y) is %f is %f\n", val, (val-gr) / (val+gr));
    }
    else if ( 0 <=  val && val  < 2*M_PI && 0 <= gr && gr < M_PI_2)
    {

        printf ("sinx / cosx (%f) = %f.\n", val, sin(val) / cos(val));

    }
    else
    {
        printf ("ln(x2 + y2) is  (%f) = %f.\n", val, log(val*val + gr*gr) );
        cout << "Your number is: "  << val << endl;
    }

    cin.get();