Function redRing_Z

kernel/GBEngine/kstd2.cc:677–832

2 * reduction procedure for the ring coeffs */

*  reduction procedure for the ring coeffs
*/
int redRing_Z (LObject* h,kStrategy strat)
{
  if (h->IsNull()) return 0; // spoly is zero (can only occur with zero divisors)
  if (strat->tl<0) return 1;

  int at;
  long d;
  int j = 0;
  int pass = 0;

// TODO warum SetpFDeg notwendig?
  h->SetpFDeg();
  assume(h->pFDeg() == h->FDeg);
  long reddeg = h->GetpFDeg();

  h->SetShortExpVector();
  loop
  {
    /* check if a reducer of the lead term exists */
    j = kFindDivisibleByInT(strat, h);
    if (j < 0)
    {
#if STDZ_EXCHANGE_DURING_REDUCTION
      /* check if a reducer with the same lead monomial exists */
      j = kFindSameLMInT_Z(strat, h);
      if (j < 0)
      {
#endif
        /* check if a reducer of the lead monomial exists, by the above
         * check this is a real divisor of the lead monomial */
        j = kFindDivisibleByInT_Z(strat, h);
        if (j < 0)
        {
          // over ZZ: cleanup coefficients by complete reduction with monomials
          if (rHasLocalOrMixedOrdering(currRing))
            postReduceByMon(h, strat);
          if(h->p == NULL)
          {
            if (h->lcm!=NULL) pLmDelete(h->lcm);
            h->Clear();
            return 0;
          }
          if(nIsZero(pGetCoeff(h->p))) return 2;
          j = kFindDivisibleByInT(strat, h);
          if(j < 0)
          {
            if(strat->tl >= 0)
              h->i_r1 = strat->tl;
            else
              h->i_r1 = -1;
            if (h->GetLmTailRing() == NULL)
            {
              if (h->lcm!=NULL) pLmDelete(h->lcm);
              h->Clear();
              return 0;
            }
            return 1;
          }