reduce4()

res2_pair * res2_comp::reduce4 ( res2term *& f, res2term *& fsyz, res2term *& pivot, res2_pair * p )

private

Definition at line 1402 of file res-a0.cpp.

{
  // 'lastterm' is used to append the next monomial to fsyz->syz
  exponents_t REDUCE_exp = ALLOCATE_EXPONENTS(exp_size);
  monomial REDUCE_mon = ALLOCATE_MONOMIAL(monom_size);
 
  res2term *lastterm = fsyz;
  while (lastterm->next != nullptr) lastterm = lastterm->next;
 
  res2term head;
  res2term *red = &head;
  res2_pair *result = nullptr;
  res2_pair *q;
  ring_elem rg;
 
  int count = total_reduce_count;
  if (M2_gbTrace >= 4) emit_wrapped(",");
 
  while (f != nullptr)
    {
      res2term *lead = f;
      f = f->next;
      lead->next = nullptr;
      M->divide(lead->monom, lead->comp->syz->monom, REDUCE_mon);
      M->to_expvector(REDUCE_mon, REDUCE_exp);
      if (find_ring_divisor(REDUCE_exp, rg))
        {
          // Subtract off f, leave fsyz alone
          Nterm *r = rg;
          M->divide(lead->monom, r->monom, REDUCE_mon);
          ring_elem c = K->negate(lead->coeff);
          res2term *h =
              R->ring_mult_by_term(r->next, c, REDUCE_mon, lead->comp);
          R->remove(lead);
          K->remove(c);
          R->add_to(f, h);
          total_reduce_count++;
        }
      else if (find_divisor(lead->comp->mi, REDUCE_exp, q))
        {
          if (q->degree == p->degree + 1)
            // if (q->syz_type == SYZ2_S_PAIR)
            {
              lastterm->next =
                  R->new_term(K->negate(lead->coeff), lead->monom, q);
              lastterm = lastterm->next;
              if (result == nullptr && q->syz_type == SYZ2_S_PAIR)
                {
                  // Only do this for the first non-computed pair
                  // Question: do we really need to keep this information
                  // around?
                  pivot = lastterm;
                  result = q;
                }
              red->next = lead;
              red = red->next;
              continue;
            }
          else
            {
              ring_elem c = K->negate(lead->coeff);
              M->divide(lead->monom, q->syz->monom, REDUCE_mon);
              res2term *h = R->mult_by_term(q->syz->next, c, REDUCE_mon);
              lastterm->next = R->new_term(c, lead->monom, q);  // grabs 'c'.
              lastterm = lastterm->next;
              R->remove(lead);
              R->add_to(f, h);
              total_reduce_count++;
            }
        }
      else
        {
          red->next = lead;
          red = red->next;
        }
    }
  red->next = nullptr;
  f = head.next;
  if (M2_gbTrace >= 4)
    {
      buffer o;
      o << (total_reduce_count - count);
      emit_wrapped(o.str());
    }
  return result;
}

References ALLOCATE_EXPONENTS, ALLOCATE_MONOMIAL, res2term::coeff, res2term::comp, res2_pair::degree, emit_wrapped(), exp_size, find_divisor(), find_ring_divisor(), K, M, M2_gbTrace, res2_pair::mi, Nterm::monom, res2term::monom, monom_size, monomial, Nterm::next, res2term::next, p, R, result(), buffer::str(), res2_pair::syz, SYZ2_S_PAIR, res2_pair::syz_type, and total_reduce_count.

Referenced by handle_pair_by_degree().