gb_reduce() [2/2]

void HermiteComputation::gb_reduce ( vec & f, vec & fsyz ) const

private

Definition at line 423 of file hermite.cpp.

{
  // Reduce f so that each of its terms are < corresponding initial term
  // (in absolute value).
  vecterm head;
  vecterm *result = &head;
  head.next = nullptr;
  while (f != nullptr)
    {
      int x = f->comp;
      hm_elem *h = initial[x];
      if (h != nullptr)
        {
          ring_elem v;
          ring_elem rem =
              globalZZ->remainderAndQuotient(f->coeff, h->f->coeff, v);
          bool do_reduce = !globalZZ->is_zero(v);
          if (do_reduce)
            {
              v = globalZZ->negate(v);
              vec g = globalZZ->mult_vec(v, h->f);
              globalZZ->add_vec_to(f, g);
              vec gsyz = globalZZ->mult_vec(v, h->fsyz);
              globalZZ->add_vec_to(fsyz, gsyz);
            }
          if (globalZZ->is_zero(rem)) continue;
        }
      // The lead term stays
      result->next = f;
      f = f->next;
      result = result->next;
      result->next = nullptr;
      continue;
    }
 
  f = head.next;
}

References hm_elem::f, hm_elem::fsyz, globalZZ, vec::next, result(), and x.