Function idPrepare

kernel/ideals.cc:607–707

2 *computes syzygies of h1, *if quot != NULL it computes in the quotient ring modulo "quot" *works always in a ring with ringorder_s */ construct a "matrix" (h11 may be NULL) * h1 h11 * E_n 0 * and compute a (column) GB of it, with a syzComp=rows(h1)=rows(h11) * currRing must be a syz-ring with syzComp set * result is a "matrix": * G 0 * T S * where G: GB of (h1+h1

 * if V_IDLIFT is set, ignore/do not return S
 */
static ideal idPrepare (ideal  h1, ideal h11, tHomog hom, int syzcomp, intvec **w, GbVariant alg)
{
  ideal   h2,h22;
  int     j,k;
  poly    p,q;

  assume(!idIs0(h1));
  k = id_RankFreeModule(h1,currRing);
  if (h11!=NULL)
  {
    k = si_max(k,(int)id_RankFreeModule(h11,currRing));
    h22=idCopy(h11);
  }
  h2=idCopy(h1);
  int i = IDELEMS(h2);
  if (h11!=NULL) i+=IDELEMS(h22);
  if (k == 0)
  {
    id_Shift(h2,1,currRing);
    if (h11!=NULL) id_Shift(h22,1,currRing);
    k = 1;
  }
  if (syzcomp<k)
  {
    Warn("syzcomp too low, should be %d instead of %d",k,syzcomp);
    syzcomp = k;
    rSetSyzComp(k,currRing);
  }
  h2->rank = syzcomp+i;

  //if (hom==testHomog)
  //{
  //  if(idHomIdeal(h1,currRing->qideal))
  //  {
  //    hom=TRUE;
  //  }
  //}

  for (j=0; j<IDELEMS(h2); j++)
  {
    p = h2->m[j];
    q = pOne();
#ifdef HAVE_SHIFTBBA
    // non multiplicative variable
    if (rIsLPRing(currRing))
    {
      pSetExp(q, currRing->isLPring - currRing->LPncGenCount + j + 1, 1);
      p_Setm(q, currRing);
    }
#endif
    pSetComp(q,syzcomp+1+j);
    pSetmComp(q);
    if (p!=NULL)
    {
#ifdef HAVE_SHIFTBBA
      if (rIsLPRing(currRing))
      {
        h2->m[j] = pAdd(p, q);