#include "stdafx.h"
#include <iostream>

using namespace std;

void resp(double a, double b, double e);
void resn(double a, double b, double e);
void resh(double a, double b, double e);
void resk(double a, double b, double e);

double form(double x)
{
	return pow(x, 2) + 0.5*pow(x, 2) - 0.5 * x;
}

double form2(double x)
{
	return pow(x, 3) - x + 75;
}

double _form2(double x)
{
	return 12 + pow(x, 2) ;
}

int main()
{
	setlocale(LC_ALL, "rus");
	int s;
	double a, b, x, e;
	bool t = true;
	while (t)
	{
		cout << "0) выход\n1) ввод значений\n2) Метод половинного деления\n3) Метод простых итераций\n4) Метод Ньютона\n5) Метод хорд\n6) Комбинированный метод\n";
		cin >> s;
		cout << endl << endl;
		switch (s)
		{
		case 0:
			t = false;
			break;
		case 1:
			cout << "a = ";
			cin >> a;
			cout << "b = ";
			cin >> b;
			cout << "E = ";
			cin >> e;
			cout << endl << endl;
			cout << "a = " << a << ", b = " << b << ", E = " << e << endl << endl;
			break;
		case 2:
			resp(a, b, e);
			break;
		case 3:

			break;
		case 4:
			resn(a, b, e);
			break;
		case 5:
			resh(a, b, e);
			break;
		case 6:
			resk(a, b, e);
			break;
		default:
			break;
		}
	}
}

void resp(double a, double b, double e)
{
	double x = 0, fa, fb, fx;
	while (true)
	{
		x = (a + b) / 2;
		if (b - a < 2 * e)
		{
			cout << "Ответ: " << x << endl << endl;
			break;
		}
		fa = form(a);
		fb = form(b);
		fx = form(x);
		if (((fa < 0) && (fx > 0)) || ((fa > 0) && (fx < 0))) b = x;
		else if (((fb < 0) && (fx > 0)) || ((fb > 0) && (fa < 0))) a = x;
	}
}

void resn(double a, double b, double e)
{
	double xn, x;
	if (form(a) * _form2(a) > 0) x = a;
	else x = b;
	while (true)
	{
		xn = x - form(x) / form2(x);
		if (abs(xn - x) < e)
		{
			cout << "Ответ: " << xn << endl << endl;
			break;
		}
		x = xn;
	}
}

void resk(double a, double b, double e)
{
	double xn, x, xn2, x2;
	if (form(a) < 0 && form(b) > 0)
	{
		x = a;
		x2 = b;
		while (true)
		{
			xn = x - form(x) / (form(x2) - form(x)) * (x2 - x);
			xn2 = x2 - form(x2) / _form2(x2);
			if (abs(x2 - x) < e)
			{
				cout << "Ответ: " << (x + x2) / 2 << endl << endl;
			}
		}
	}
}

void resh(double a, double b, double e)
{
	double xn, x;
	if (form(b) < 0)
	{
		x = b;
		while (true)
		{
			xn = x - form(x) / (form(x) - form(a)) * (x - a);
			if (abs(xn - x) < e)
			{
				cout << "Ответ: " << xn << endl << endl;
				break;
			}
			x = xn;
		}
	}
	else
	{
		x = a;
		while (true)
		{
			xn = x - form(x) / (form(b) - form(x)) * (b - x);
			if (abs(xn - x) < e)
			{
				cout << "Ответ: " << xn << endl << endl;
				break;
			}
			x = xn;
		}
	}
}