golden-ratio.cpp

double golden(double epsilon=0.00001) {
  int a = 0;
  int b = 1;
  double ratio = 0;
 
  while (1) {
    tie(a, b) = tuple{b, a+b};
    auto delta = b / (double)a - ratio;
    ratio = b / (double)a;
    if ( abs(delta) < epsilon ) 
      return ratio;
  }
}  

int main() {
  cout << golden() << std::endl;
}