#include <iostream>
#include <cmath>
#include <string>
#include <fstream>

using namespace std;

double Analytical(double x)
{
    if(x==0){return 1/3;}
    else{return ((2*x*x+2*x)*sin(x)+(-1*pow(x, 4)-2*pow(x, 3)-x*x+2)*cos(x)+x*x*x*x-2)/pow(x, 3);}

}

double Function(double x, double t)
{
    return pow(t+x, 2)*sin(x*t);
}

double Right_rect(double x, double n, double h,double a)
{
    double sum = 0;
    for (int i = 1; i <= n; i++)

        sum += h*(Function(x, a + h * i));
    return sum;
}

int main()
{
    setlocale(LC_CTYPE, "Russian");

    const double PI = 3.141592653589793;

    double a = 0, b = PI, c, d, N[3], difference[3] = {0, 0, 0};

    cout << "Введите нижнюю границу для х " << endl;
    cin >> c;
    cout << "Введите верхнюю границу для х " << endl;
    cin >> d;
    if(c<0||d>PI){cout << "Выход за область определениея"; return 0;}
    cout << "Введите количество разбиений - 3 разных значения: " << endl;
    cin >> N[0] >> N[1] >> N[2];

    fstream fin("/home/daminator/Desktop/Education/KUBSU/Programming methods/Practise/Практика летняя/output.txt");
    fin << "x \t\t"  << "N="<<N[0] << "\t\t" << "N=" << N[1] << "\t\t" << "N=" << N[2] << "\t\t" << "Analytical" << '\n';
    for (int i = 0; i <= 20; i++)
    {
        double x = c + i * (d - c) / 20;
        double Analytic_Integral = Analytical(x);
        fin << to_string(x) + '\t';
        for (int j = 0; j < 3; j++)
        {
            double h = (b - a) / N[j];
            double Rectangle_Integral = Right_rect(x, N[j], h, a);
            fin << to_string(Rectangle_Integral) + '\t';
            if (abs(Analytic_Integral - Rectangle_Integral) > difference[j])
                difference[j] = abs(Analytic_Integral - Rectangle_Integral);
        }
        fin << to_string(Analytic_Integral) + '\n';

    }
    fin << "Для различных значений разбиений максимальная невязка  равна: \n";

    for (int i = 0; i < 3; i++)
        fin << N[i] << ": " << difference[i] << "\n";

    fin.seekg(0);

    string getcontent;

    if (fin.is_open())
        while (getline(fin, getcontent))
            cout << getcontent << endl;

    fin.close();
    return 0;

}