CRA() [2/5]

ring_elem ChineseRemainder::CRA ( const PolyRing * R, const ring_elem f, const ring_elem g, mpz_srcptr um, mpz_srcptr vn, mpz_srcptr mn )

static

Definition at line 53 of file cra.cpp.

{
  mpz_t result_coeff;
  mpz_t mn_half;
  mpz_init(result_coeff);
  mpz_init(mn_half);
  Nterm *f = ff;
  Nterm *g = gg;
  Nterm head;
  Nterm *result = &head;
 
  mpz_tdiv_q_2exp(mn_half, mn, 1);
 
  const Monoid *M = R->getMonoid();
  const Ring *K = R->getCoefficientRing();
 
  while (1)
    {
      if (g == nullptr)
        {
          // mult each term of f by n:
          for (; f != nullptr; f = f->next)
            {
              result->next = R->new_term();
              result = result->next;
              result->next = nullptr;
              M->copy(f->monom, result->monom);
              mpz_mul(result_coeff, f->coeff.get_mpz(), vn);
              mpz_mod(result_coeff, result_coeff, mn);
              if (mpz_cmp(result_coeff, mn_half) > 0)
                {
                  mpz_sub(result_coeff, result_coeff, mn);
                }
              result->coeff = K->from_int(result_coeff);
            }
          break;
        }
      if (f == nullptr)
        {
          // mult each term of g by n:
          for (; g != nullptr; g = g->next)
            {
              result->next = R->new_term();
              result = result->next;
              result->next = nullptr;
              M->copy(g->monom, result->monom);
              mpz_mul(result_coeff, g->coeff.get_mpz(), um);
              mpz_mod(result_coeff, result_coeff, mn);
              if (mpz_cmp(result_coeff, mn_half) > 0)
                {
                  mpz_sub(result_coeff, result_coeff, mn);
                }
              result->coeff = K->from_int(result_coeff);
            }
          break;
        }
      switch (M->compare(f->monom, g->monom))
        {
          case -1:
            result->next = R->new_term();
            result = result->next;
            result->next = nullptr;
            M->copy(g->monom, result->monom);
            mpz_mul(result_coeff, g->coeff.get_mpz(), um);
            result->coeff = K->from_int(result_coeff);
            g = g->next;
            break;
          case 1:
            result->next = R->new_term();
            result = result->next;
            result->next = nullptr;
            M->copy(f->monom, result->monom);
            mpz_mul(result_coeff, f->coeff.get_mpz(), vn);
            result->coeff = K->from_int(result_coeff);
            f = f->next;
            break;
          case 0:
            Nterm *tmf = f;
            Nterm *tmg = g;
            f = f->next;
            g = g->next;
            CRA0(tmf->coeff.get_mpz(),
                 tmg->coeff.get_mpz(),
                 um,
                 vn,
                 mn,
                 result_coeff);
            Nterm *t = R->new_term();
            M->copy(tmf->monom, t->monom);
            t->coeff = K->from_int(result_coeff);
            t->next = nullptr;
            result->next = t;
            result = t;
            break;
        }
    }
 
  mpz_clear(result_coeff);
  mpz_clear(mn_half);
  result->next = nullptr;
  return head.next;
}

References Nterm::coeff, Monoid::compare(), Monoid::copy(), CRA0(), Ring::from_int(), ring_elem::get_mpz(), PolynomialRing::getCoefficientRing(), PolynomialRing::getMonoid(), Nterm::monom, PolyRing::new_term(), Nterm::next, and result().

Referenced by CRA(), CRA(), CRA(), rawMatrixCRA(), and rawRingElementCRA().