using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp4
{
    public partial class Form1 : Form
    {
        double  x3, x2, x1, x, ex, a, b, E, ww;
        public Form1()
        {
            InitializeComponent();
        }

        private void x3TB_TextChanged(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {

            x3 = double.Parse(x3TB.Text);
            x2 = double.Parse(x2TB.Text);
            x1 = double.Parse(x1TB.Text);
            ex = double.Parse(exTB.Text);
            a = double.Parse(aTB.Text);
            b = double.Parse(bTB.Text);
            E = double.Parse(ETB.Text);
            ww = double.Parse(wwTB.Text);
            if (policz(a) < 0 && policz(b) > 0 && drugaPoch(b) > 0)
            {
                przyblizenie(b,a);
            }
            else if (policz(a) > 0 && policz(b) < 0 && drugaPoch(a) > 0)
            {
                przyblizenie(a,b);
            }
            else if (policz(a) > 0 && policz(b) < 0 && drugaPoch(b) < 0)
            {
                przyblizenie(b,a);
            }
            else if (policz(a) < 0 && policz(b) > 0 && drugaPoch(a) < 0)
            {
                przyblizenie(a,b);
            }
            else
            {
                xTB.Text = "Brak rozwiązań";
            }
        }
        private double policz(double iks)
        {
            return x3 * Math.Pow(iks, 3) + x2 * Math.Pow(iks, 2) + x1 * iks + ex * Math.Exp(iks) + ww;
        }
        private double pierwPoch(double iks)
        {
            return 3 * x3 * Math.Pow(iks, 2) + 2 * x2 * Math.Pow(iks, 1) + x1 * 1 + ex * Math.Exp(iks);

        }
        private double drugaPoch(double x)
        {
            return  3 * 2 * x3 * x + 2 * x2 +  Math.Exp(x)*ex;
        }
        private void przyblizenie(double a,double b)
        {
            double wynik,wynik2,wkon;
            do
            {

                a = a - (policz(a) / (policz(b) - policz(a))) * (b - a);

            } while (!(Math.Abs(policz(a)) < E));// || Math.Abs(wynik2 - wkon) < E);
            xTB.Text = a.ToString();
        }
    }
}