added member function in class xtensor::xPoint :
  double & operator [] (int i);
  double operator [] (int i) const;
  xPoint operator / (double other) const;
  xPoint& operator /= (double other)
  xPoint& operator -= (const xPoint &other)
  bool operator == (const xPoint & other) const

 xTensor/src/xPoint.h   clang-formated