merge()

hm_elem * HermiteComputation::merge ( hm_elem * f, hm_elem * g )

private

Definition at line 124 of file hermite.cpp.

{
  if (g == nullptr) return f;
  if (f == nullptr) return g;
  hm_elem head;
  hm_elem *result = &head;
  hm_elem *h;
  while (1) switch (compare_elems(f, g))
      {
        case 1:
          result->next = g;
          result = result->next;
          g = g->next;
          if (g == nullptr)
            {
              result->next = f;
              return head.next;
            }
          break;
        case 0:
          // In this case, we remove one, and re-insert:
          if (mpz_cmp(f->f->coeff.get_mpz(), g->f->coeff.get_mpz()) == 0)
            {
              vec f1 = globalZZ->copy_vec(f->f);
              vec f2 = globalZZ->copy_vec(f->fsyz);
              globalZZ->subtract_vec_to(g->f, f1);
              globalZZ->subtract_vec_to(g->fsyz, f2);
            }
          else
            {
              vec f1 = globalZZ->copy_vec(f->f);
              vec f2 = globalZZ->copy_vec(f->fsyz);
              globalZZ->add_vec_to(g->f, f1);
              globalZZ->add_vec_to(g->fsyz, f2);
            }
 
          h = g;
          // We need to reset the lead term
          if (g->f != nullptr) mpz_abs(h->lead, g->f->coeff.get_mpz());
          g = g->next;
          insert(h);
          if (g == nullptr)
            {
              result->next = f;
              return head.next;
            }
        // Now fall through to merge f into the result:
          [[fallthrough]];
        case -1:
          result->next = f;
          result = result->next;
          f = f->next;
          if (f == nullptr)
            {
              result->next = g;
              return head.next;
            }
          break;
      }
}

References compare_elems(), hm_elem::f, hm_elem::fsyz, globalZZ, insert(), hm_elem::lead, hm_elem::next, and result().

Referenced by sort().