#include <cstdlib>

namespace
{
  void random_number(double x[], std::size_t n)
  {
    for (std::size_t i = 0; i != n; ++i)
      x[i] = static_cast<double>(rand())/RAND_MAX;
  }

  double sum(double fx[], std::size_t n)
  {
    double tmp(0.0);
    for (std::size_t i = 0; i != n; ++i)
      tmp += fx[i];
    return tmp;
  }

  void
  func(double fx[], double x[], std::size_t n)
  {
    for (std::size_t i = 0; i != n; ++i)
      fx[i] = 1.0 / (1.0 + x[i]*x[i]);
  }
}