Method abs

code/mathematics/intx.cpp:57–57

  intx operator -() const {
    intx res(*this); res.sign *= -1; return res; }
  friend intx abs(const intx &n) { return n < 0 ? -n : n; }
  intx operator +(const intx& b) const {
    if (sign > 0 && b.sign < 0) return *this - (-b);
    if (sign < 0 && b.sign > 0) return b - (-*this);