list_form()

engine_RawArrayPairOrNull M2FreeAlgebra::list_form ( const Ring * coeffR, const ring_elem f ) const

virtual

Definition at line 348 of file M2FreeAlgebra.cpp.

{
  // Either coeffR should be the actual coefficient ring (possible a "toField"ed ring)
  // or a polynomial ring.  If not, NULL is returned and an error given
  // In the latter case, the last set of variables are part of
  // the coefficients.
 
  auto f = reinterpret_cast<const Poly*>(ff.get_Poly());
  if (coeffR != coefficientRing())
    {
      ERROR("expected coefficient ring");
      return nullptr;
    }
  int nterms = static_cast<int>(f->numTerms());
  engine_RawMonomialArray monoms = GETMEM(engine_RawMonomialArray, sizeofarray(monoms,nterms));
  engine_RawRingElementArray coeffs = GETMEM(engine_RawRingElementArray, sizeofarray(coeffs,nterms));
  engine_RawArrayPair result = newitem(struct engine_RawArrayPair_struct);
  monoms->len = nterms;
  coeffs->len = nterms;
  result->monoms = monoms;
  result->coeffs = coeffs;
 
  // fill result
  std::vector<int> vp;
  int next = 0;
  for (auto i=f->cbegin(); i != f->cend(); ++i, ++next)
    {
      ring_elem c = coefficientRing()->copy(i.coeff());
      vp.resize(0);
      monoid().getMonomialReversed(i.monom(), vp); // should this instead reverse the monomial?
      coeffs->array[next] = RingElement::make_raw(coeffR, c);
      monoms->array[next] = EngineMonomial::make(vp); // reverses the monomial
    }
  
  return result;
}

References coefficientRing(), Ring::copy(), ERROR, ring_elem::get_Poly(), GETMEM, FreeMonoid::getMonomialReversed(), EngineMonomial::make(), RingElement::make_raw(), monoid(), newitem, result(), Ring::Ring(), and sizeofarray.

Referenced by IM2_RingElement_list_form(), and M2FreeAlgebraQuotient::list_form().