invert()

ring_elem PolyRing::invert ( const ring_elem f ) const

virtual

Implements Ring.

Definition at line 961 of file poly.cpp.

{
  Nterm *ft = f;
  if (is_zero(f))
    {
      ERROR("cannot divide by zero");
      return ZERO_RINGELEM;
    }
  if (ft->next == nullptr)
    {
      if (M_->is_one(ft->monom))
        {
          Nterm *t = new_term();
          t->coeff = K_->invert(ft->coeff);
          M_->one(t->monom);
          return t;
        }
      else if (M_->is_invertible(ft->monom))
        {
          Nterm *t = new_term();
          t->coeff = K_->invert(ft->coeff);
          M_->power(ft->monom, -1, t->monom);
          return t;
        }
    }
 
  ERROR("element is not invertible in this ring");
  return ZERO_RINGELEM;
}

References Nterm::coeff, ERROR, is_zero(), PolynomialRing::K_, PolynomialRing::M_, Nterm::monom, new_term(), Nterm::next, and ZERO_RINGELEM.

Referenced by power(), and power().