pi_converge.cc

#include <iostream>
#include <cmath>

int main(int argc, char* argv[])
{
  constexpr int iters = 100000;
  double x = 2.321232;

  for (std::size_t i = 0; i < iters; ++i)
    x = std::hypot(x, std::sin(x));

  std::cout << x << std::endl;

  return 0;
}