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

using namespace std;

double funcval(double, double[], int );
double derival(double, double[], int);

int main (){
    //vector<double> coef;
    int coefNum;
    ifstream file("polynomial.txt");
    if (!file){
        return 0;
    }
    string useless;
    getline(file, useless);
    file >> coefNum;
    double poly[coefNum + 1];
    while (file.good()){
        int d;
        file >> d;
        file >> poly[d];
        cout << poly[d] << "    ";
    }
    cout << endl;
    for (int i = 0; i<=coefNum; i++){
    cout << poly[i] << "    ";
    }
    file.close();

    double xval;
    cout<<"Enter an initial estimate for the root.  ";
    cin>>xval;
    double h=.002;
    int dir = -1;
    while (h > .000002){
        if (derival(xval + h * dir, poly, coefNum) * dir < 0){
            xval += h;
            cout << xval << endl;
        } else {
            dir *= -1;
            h /= 10;
        }
        //cout << h << endl;
    }
    cout << funcval(xval, poly, coefNum);

    return 0;
}


double funcval(double xval, double coeff[], int deg){
    double y = 0;
    for(int i = 0; i <= deg; i++){
        y = y + coeff[i] * pow(xval, i);
    }
    return y;
}
double derival(double xval, double coeff[], int deg){
    double dy = 0;
    for (int i = 1; i <= deg; i++){
        dy = dy + coeff[i] * pow(xval, i - 1);
    }
    return dy;
}