remainder() [2/2]

void ReducedGB_Field_Local::remainder ( POLY & f, bool use_denom, ring_elem & denom )

virtual

Reimplemented from ReducedGB_Field.

Definition at line 492 of file reducedgb-field-local.cpp.

{
  if (M2_gbTrace >= 4) {
      buffer o;
      text_out(o);
      emit(o.str());
    }
  if (f.f == nullptr) return;
  T1 = MonomialTable::make(R->n_vars());
  gbvector head;
  gbvector *frem = &head;
  frem->next = nullptr;
  POLY h = f;
  exponents_t h_exp = R->exponents_make();
  int h_alpha, g_alpha;
  int h_deg = wt->gbvector_weight(f.f);
  while (!R->gbvector_is_zero(h.f))
    {
      if (M2_gbTrace == 3) emit_wrapped(".");
      POLY g;
      R->gbvector_get_lead_exponents(F, h.f, h_exp);
      int h_comp = h.f->comp;
 
      if (M2_gbTrace >= 4)
        {
          buffer o;
          o << "\nreducing ";
          R->gbvector_text_out(o, F, h.f);
          emit(o.str());
        }
 
      if (find_good_divisor(h_exp,
                            h_comp,
                            h_deg,
                            h_alpha,
                            g,
                            g_alpha))  // sets these three values
        {
          if (M2_gbTrace >= 4)
            {
              buffer o;
              o << "  h_alpha " << h_alpha << " g_alpha "
                << g_alpha;  // << " reducing using ";
              // R->gbvector_text_out(o,F,g.f);
              // o << newline;
              emit(o.str());
            }
          if (g_alpha > h_alpha)
            {
              if (head.next != nullptr)
                {
                  // In this case, we can't reduce the tail without
                  // risking an infinite loop.  So we declare ourselves done
                  // Attach the rest of h.f to frem
                  frem->next = h.f;
                  break;
                }
              // place h into T1, and store its (value,deg,alpha) values.
              // store_in_table copies h
              store_in_table(h, h_exp, h_comp, h_alpha);
              if (M2_gbTrace == 3) emit_wrapped("x");
              if (M2_gbTrace == 4) emit("\nstored result\n");
              h_deg += g_alpha - h_alpha;
              h_exp = R->exponents_make();
            }
          R->gbvector_reduce_lead_term(
              F, Fsyz, head.next, h.f, h.fsyz, g.f, g.fsyz, use_denom, denom);
        }
      else
        {
          frem->next = h.f;
          frem = frem->next;
          h.f = h.f->next;
          frem->next = nullptr;
        }
    }
 
  f.f = head.next;
  f.fsyz = h.fsyz;
  R->exponents_delete(h_exp);
  reset_table();
}

References gbvector::comp, emit(), emit_wrapped(), ReducedGB::F, POLY::f, find_good_divisor(), ReducedGB::Fsyz, POLY::fsyz, M2_gbTrace, MonomialTable::make(), gbvector::next, POLY, ReducedGB::R, reset_table(), store_in_table(), buffer::str(), T1, ReducedGB::text_out(), and wt.

Referenced by minimalize().