reduce()

res_pair * res_comp::reduce ( resterm *& f, resterm *& fsyz, resterm *& pivot )

private

Definition at line 743 of file res-a1.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);
 
  resterm *lastterm = (fsyz->next == nullptr ? fsyz : fsyz->next);
 
  res_pair *q;
  ring_elem rg;
  Bag *b;
 
  while (f != nullptr)
    {
      M->divide(f->monom, f->comp->base_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(f->monom, r->monom, REDUCE_mon);
          R->ring_subtract_multiple_to(f, f->coeff, REDUCE_mon, f->comp, rg);
        }
      else if (f->comp->mi->search_expvector(REDUCE_exp, b))
        {
          q = reinterpret_cast<res_pair *>(b->basis_ptr());
          lastterm->next = R->new_term(K->negate(f->coeff), f->monom, q);
          lastterm = lastterm->next;
          pivot = lastterm;
          if (q->syz_type == SYZ_S_PAIR) return q;  // i.e. not computed yet
          M->divide(f->monom, q->syz->monom, REDUCE_mon);
          R->subtract_multiple_to(f, f->coeff, REDUCE_mon, q->syz);
        }
      else
        {
          // level 1: monomial not seen yet
          q = new_res_pair(SYZ_S_PAIR, f);
          insert_res_pair(1, q);
          lastterm->next = R->new_term(K->negate(f->coeff), f->monom, q);
          lastterm = lastterm->next;
          return q;
        }
    }
  return nullptr;
}

References ALLOCATE_EXPONENTS, ALLOCATE_MONOMIAL, res_pair::base_monom, int_bag::basis_ptr(), resterm::coeff, resterm::comp, exp_size, find_ring_divisor(), insert_res_pair(), K, M, res_pair::mi, Nterm::monom, resterm::monom, monom_size, monomial, new_res_pair(), resterm::next, R, MonomialIdeal::search_expvector(), res_pair::syz, SYZ_S_PAIR, and res_pair::syz_type.

Referenced by handle_pair().