#include <iostream>
#include <cmath> //sinus
using namespace std;

double f(double x) {
	return (x / (1.2 - sin(2 * x)));
}

double concave(double x1, double a, double b) { //1.21
	return ((-2)*(f(a)*(b-x1)+f(x1)*(a-b)+f(b)*(x1-a))/((b-x1)*(a-b)*(x1-a)));
}

double xTwo(double x1, double a, double b) { //1.22
	return ((f(a)*((b*b)-(x1*x1))
					+f(x1)*((a*a)-(b*b))
					+f(b)*((x1*x1)-(a*a)))/
					2*(f(a)*(b-x1)
					+f(x1)*(a-b)
					+f(b)*(x1-a))
			);
}



int main() {
	int expansion_factor = 4, i=1;
	double accuracy = 0.000001;
	double x1[100], x2[100], a[100], b[100], shift1, shift2;
	x1[0] = 0.22; //initial point > 0
	cout << f(0) << " < " << f(x1[0]) << "\n\n"; //so
	a[1] = (-1)*expansion_factor*x1[0];	x1[1] = 0;	b[1]=x1[0];
	cout << "i\ta\tx1\tx2\tb\n";

	do {
		while (concave(x1[i], a[i], b[i]) <= 0) { //1.21, 1.24
			cout << i << "\t" << a[i] << "\t" << x1[i] << "\t" << x2[i] << "\t" << b[i];
			cout << "\tconcave\n";
			a[i] = x1[i];
			x1[i] = b[i];
			b[i] = b[i] + expansion_factor*(b[i]-x1[i]);
		}
		x2[i] = xTwo(x1[i], a[i], b[i]);
		if (x2[i] < x1[i]) {
			cout << i << "\t" << a[i] << "\t" << x1[i] << "\t" << x2[i] << "\t" << b[i];
			cout << "\tx2<x1\n";
			shift1 = x2[i];
			x2[i] = x1[i];
			x1[i] = shift1;
		}
		if (x2[i] < a[i] || x2[i] > b[i]) { //1.25
			cout << i << "\t" << a[i] << "\t" << x1[i] << "\t" << x2[i] << "\t" << b[i];
			cout << "\tout of interval\n";
			shift1 = a[i];
			shift2 = x1[i];
			a[i] = x2[i];
			x1[i] = shift1;
			b[i] = shift2;
		};
		cout << i << "\t" << a[i] << "\t" << x1[i] << "\t" << x2[i] << "\t" << b[i];
		if (f(x1[i])>=f(x2[i])) { //1.11 - 1.13
		cout << "\ta deleted\n";
			a[i+1] = x1[i];
			b[i+1] = b[i];
			x1[i+1] = x2[i];
		}
		else { //1.15 - 1.18
		cout << "\tb deleted\n";
			a[i+1] = a[i];
			b[i+1] = x2[i];
			x1[i+1] = x1[i];
		}

		i++;
	} while (i<90);//x2[i]-x1[i] > accuracy);
	return 0;
}