RingMap()

RingMap::RingMap ( const Matrix * m )

private

Definition at line 10 of file ringmap.cpp.

                                : R(m->get_ring())
{
  M = nullptr;
  P = R->cast_to_PolynomialRing();
  if (P != nullptr)
    {
      M = P->getMonoid();
      K = P->getCoefficientRing();
    }
  else
    K = R;
 
  nvars = m->n_cols();
  is_monomial = true;
 
  ring_elem one = K->from_long(1);
 
  // Allocate space for the ring map elements
  _elem = new var[nvars];
 
  for (int i = 0; i < nvars; i++)
    {
      // First initialize these fields:
      _elem[i].is_zero = false;
      _elem[i].coeff_is_one = true;
      _elem[i].monom_is_one = true;
      _elem[i].bigelem_is_one = true;
      _elem[i].coeff = ZERO_RINGELEM;
      _elem[i].monom = nullptr;
 
      ring_elem f = m->elem(0, i);  // This does a copy.
      _elem[i].bigelem = f;
 
      if (R->is_zero(f))
        _elem[i].is_zero = true;
      else if (P == nullptr)
        {
          // Not a polynomial ring, so put everything into coeff
          if (!K->is_equal(f, one))
            {
              _elem[i].coeff_is_one = false;
              _elem[i].coeff = K->copy(f);
            }
        }
      else
        {
// A polynomial ring.
#ifdef DEVELOPMENT
#warning "also handle fraction rings"
#endif
          Nterm *t = f;
          if (t->next == nullptr)
            {
              // This is a single term
              if (!K->is_equal(t->coeff, one))
                {
                  _elem[i].coeff_is_one = false;
                  _elem[i].coeff = K->copy(t->coeff);
                }
 
              if (!M->is_one(t->monom))  // should handle M->n_vars() == 0 case
                                         // correctly.
                {
                  _elem[i].monom_is_one = false;
                  _elem[i].monom = M->make_new(t->monom);
                }
            }
          else
            {
              // This is a bigterm
              is_monomial = false;
              _elem[i].bigelem_is_one = false;
            }
        }
      K->remove(one);
    }
}

References _elem, Nterm::coeff, Matrix::elem(), get_ring(), is_monomial, K, M, Matrix, Nterm::monom, Matrix::n_cols(), Nterm::next, nvars, P, R, and ZERO_RINGELEM.

Referenced by is_equal(), and make().