4

#include <iostream>
#include <conio.h>
#include <windows.h>
#include <iomanip>
#include <cmath>

using namespace std;

void   ChangeTheValue(double&, double&);
void   Select_Menu();



double Count_Y(double, int);
double Count_S(double, int);
double Count_Ost(double, int);

typedef double(*CAF) (double, int);
void   Print_Rez(CAF, double, double, double, int);
void   Print_Rez_All(CAF, CAF, CAF, double, double, double, int);



int    main()
{
    system("color 08");
    setlocale(0, "rus");
    HANDLE console = GetStdHandle(STD_OUTPUT_HANDLE);

    double a = 0, b = 0, h = 0;
    int n = 0;



    cout << "\n\t---------------------------------------------------------------------------------------------" << endl << endl
         << "\tFor each {x}, varying from {a} to {b} in step {h}: " << endl
         << "\t1.Find function values  Y(x);" << endl
         << "\t2.Amounts S(x);" << endl
         << "\t3.|Y(x)–S(x)|;" << endl
         << "\tThe values {a, b, h, n} are entered from the keyboard." << endl << endl
         << "\t----------------------------------------------------------------------------------------------" << endl << endl;;

    do {

        cout << "\tEnter the lower limit {a}... ";
        cin >> a;


        cout << "\tEnter the upper limit {b}... ";
        cin >> b;



        if (a > b) {

            SetConsoleTextAttribute(console, FOREGROUND_RED);
            cout << "\tERROR! You've entered a lowerlimit larger than the upper one" << endl;
            cout << "\tcause of that they'll swap places: ";
            SetConsoleTextAttribute(console, FOREGROUND_INTENSITY);

            ChangeTheValue(a, b);

            cout << "a = " << setprecision(10) << a << ", " << "b = " << setprecision(10) << b << ". " << endl << endl;


        }

        else if (a == b) {
            SetConsoleTextAttribute(console, FOREGROUND_RED);
            cout << "\t!ERROR You have entered equal limits, the program cannot be executed. Try again... " << endl << endl;
            SetConsoleTextAttribute(console, FOREGROUND_INTENSITY);
            continue;
        }

        cout << "\tEnter step {h} to change variable {x} from limit {a} to {b}...";
        cin >> h;

        cout << endl;

        cout << "\tEnter the upper limit of the number {n}, and {n} is an integer...";
        cin >> n;


        if (n == 0) {

            SetConsoleTextAttribute(console, FOREGROUND_RED);
            cout << "\n\t!ERROR {n} can't be equal to 0. Try again... " << endl << endl;
            SetConsoleTextAttribute(console, FOREGROUND_INTENSITY);
            continue;
        }
        cout << endl;

        break;

    } while (true);

    cout << "\n\t-----------------------------------------------------------------------------------------------" << endl << endl;


    Select_Menu();

    int choice = 0;


    cout << "\tYour choice:";

    cin >> choice;




    switch (choice) {
    case 1:

        cout << setw(21) << " Y(x) " << endl;
        Print_Rez(Count_Y, a, b, h, n);
        break;

    case 2:
        cout << setw(21) << " S(x) " << endl;
        Print_Rez(Count_S, a, b, h, n);
        break;

    case 3:
        cout << setw(24) << " |Y(x) - S(x)| " << endl;
        Print_Rez(Count_Ost, a, b, h, n);
        break;

    case 4:
        cout << "\t_____________________________________________________________________" << endl
            << setw(10) << "|"
            << setw(10) << "Y(x)"
            << setw(10) << "|"
            << setw(10) << "S(x)"
            << setw(10) << "|"
            << setw(16) << "|Y(x) - S(x)|" << setw(10) << "|" << endl;

        Print_Rez_All(Count_Y, Count_S, Count_Ost, a, b, h, n);
        break;

    }



    cout << "\n\n\t ----------------------------------------------------------------------------------------------" << endl << endl;


    return 0;
}

void   ChangeTheValue(double& a, double& b) {

    double temp = 0;
    temp = a;
    a = b;
    b = temp;

}
void   Select_Menu() {

    cout << "\n\tTo display different expressions on the screen, type from the keyboard: " << endl << endl
         << "\t\t1.To derive a number Y(x) "          << endl
         << "\t\t2.To derive a number S(x) "          << endl
         << "\t\t3.To derive a number |Y(x) - S(x)| " << endl
         << "\t\t4.To get all the expressions out "   << endl
                                                      << endl;

}




double Count_Y(double x, int n) {

    double Y = 0;
    Y = (1 + x * x) / 2.0 * atan(x) - (x / 2.0);
    return Y;

}

double Count_S(double x, int n) {

    double E = 1, p = 0, S = 1;

    for (int k = 1; k <= n; k++) {

        E = -E * (x * x) / (2.0 * k * (2.0 * k - 1));
        p = (2.0 * k * k + 1) * E;

        S += p;

    }

    return S;
}

double Count_Ost(double x, int n) {

    double ost = Count_Y(x, n) - Count_S(x, n);

    return fabs(ost);

}




void Print_Rez(CAF aF, double a, double b, double h, int n) {

    for (double x = a; x <= b; x += h) {

        cout << setw(22) << setprecision(5) << fixed << aF(x, n) << endl;

    }

}

void Print_Rez_All(CAF aF_Y, CAF aF_S, CAF aF_YS, double a, double b, double h, int n) {

    for (double x = a; x <= b; x += h) {

        cout << setw(22) << setprecision(5) << fixed << Count_Y(x, n)
             << setw(20) << setprecision(5) << Count_S(x, n)
             << setw(23) << setprecision(5) << fixed << Count_Ost(x, n) << endl;


    }

}