Exercicio da Lista 2

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

int main()
{
  double pi = 3.1415926535897932384626;

  double a = -1;
  double b = 13;
  double c = -26;
  double d = 1;

  double p = (3.0*a*c - b*b)/3.0*a*a;
  double q = (2.0*b*b*b - 9.0*a*b*c + 27.0*a*a*d)/(27.0*a*a*a);

  cout << "p=" << p << endl;
  cout << "q=" << q << endl;

  double teta = acos((3.0*q)/(2.0*p) * sqrt(-3.0/p));
  double scale = 2.0*sqrt(-p/3.0);
  double off = -b/(3.*a);

  double x1 = off+scale*cos(teta/3.);
  double x2 = off+scale*cos(teta/3. - (2.0/3.0)*pi);
  double x3 = off+scale*cos(teta/3. - (4.0/3.0)*pi);

  cout << "X1=" << x1 << endl;
  cout << "X2=" << x2 << endl;
  cout << "X3=" << x3 << endl;
}