main.cpp

#include <iostream>
#include <math.h>
#include "main.h"

using std::cin;
using std::cout;


int main() {
  double x0, x1;

  cout << "Enter x0: ";
  cin >> x0;
  cout << "Enter x1: ";
  cin >> x1;
  secant(x0, x1);

  return 0;
}


double equation(double x) {
  return(pow(x, 4) - 2 * pow(x, 3) + 3 * pow(x, 2) - 1);
}



void secant(double x0, double x1) {
  int i = 1;
  double fx1, fx0, xnew;

  cout << "Iteration #" << i << ": x0 = " << x0 << "\n";
  i++;
  while (modulus(x1-x0) > pow(10, -10)) {
    fx0 = equation(x0);
    fx1 = equation(x1);
    if ((modulus(x1-x0) < pow(10, -10)) || (modulus(fx1-fx0) < pow(10, -10))) {
      cout << "\n" << "Sorry, Root cant be reached from this point." << "\n";
      return;
    }
    xnew = x1 - fx1 * ((x1 - x0) / (fx1 - fx0));
    x0 = x1;
    x1 = xnew;
    cout << "Iteration #" << i << ": x0 = " << x0 << "\n";
    i++;
  }

  cout << "Final Result = " << x0 << "\n";
}


inline double modulus(double x) {
  if (x < 0) x = -x;
  return x;
}