Function redHomog

kernel/GBEngine/kstd2.cc:1107–1285

2 * reduction procedure for the homogeneous case * and the case of a degree-ordering */

*  and the case of a degree-ordering
*/
int redHomog (LObject* h,kStrategy strat)
{
  if (strat->tl<0) return 1;
  //if (h->GetLmTailRing()==NULL) return 0; // HS: SHOULD NOT BE NEEDED!
  assume(h->FDeg == h->pFDeg());

  poly h_p;
  int i,j,at,pass,cnt,ii;
  // long reddeg,d;
  int li;
  BOOLEAN test_opt_length=TEST_OPT_LENGTH;

  pass = j = 0;
  cnt = RED_CANONICALIZE;
  h->SetShortExpVector();
  h_p = h->GetLmTailRing();
  h->PrepareRed(strat->use_buckets);
  loop
  {
    j = kFindDivisibleByInT(strat, h);
    if (j < 0) return 1;

    li = strat->T[j].pLength;
    ii = j;
    /*
     * the polynomial to reduce with (up to the moment) is;
     * pi with length li
     */
    i = j;
#if 1
    if (test_opt_length)
    {
      if (li<=0) li=strat->T[j].GetpLength();
      if (li>2)
      {
        unsigned long not_sev = ~ h->sev;
        loop
        {
          /*- search the shortest possible with respect to length -*/
          i++;
          if (i > strat->tl)
            break;
          if ((strat->T[i].pLength < li)
             &&
              p_LmShortDivisibleBy(strat->T[i].GetLmTailRing(), strat->sevT[i],
                                   h_p, not_sev, strat->tailRing))
          {
            /*
             * the polynomial to reduce with is now;
             */
            li = strat->T[i].pLength;
            if (li<=0) li=strat->T[i].GetpLength();
            ii = i;
            if (li<3) break;
          }
        }
      }
    }