Function idMultSect

kernel/ideals.cc:471–587

2 * ideal/module intersection for a list of objects * given as 'resolvente' */

* given as 'resolvente'
*/
ideal idMultSect(resolvente arg, int length, GbVariant alg)
{
  int i,j=0,k=0,l,maxrk=-1,realrki;
  unsigned syzComp;
  ideal bigmat,tempstd,result;
  poly p;
  int isIdeal=0;

  /* find 0-ideals and max rank -----------------------------------*/
  for (i=0;i<length;i++)
  {
    if (!idIs0(arg[i]))
    {
      realrki=id_RankFreeModule(arg[i],currRing);
      k++;
      j += IDELEMS(arg[i]);
      if (realrki>maxrk) maxrk = realrki;
    }
    else
    {
      if (arg[i]!=NULL)
      {
        return idInit(1,arg[i]->rank);
      }
    }
  }
  if (maxrk == 0)
  {
    isIdeal = 1;
    maxrk = 1;
  }
  /* init -----------------------------------------------------------*/
  j += maxrk;
  syzComp = k*maxrk;

  ring orig_ring=currRing;
  ring syz_ring=rAssure_SyzOrder(orig_ring,TRUE);
  rSetSyzComp(syzComp,syz_ring);
  rChangeCurrRing(syz_ring);

  bigmat = idInit(j,(k+1)*maxrk);
  /* create unit matrices ------------------------------------------*/
  for (i=0;i<maxrk;i++)
  {
    for (j=0;j<=k;j++)
    {
      p = pOne();
      pSetComp(p,i+1+j*maxrk);
      pSetmComp(p);
      bigmat->m[i] = pAdd(bigmat->m[i],p);
    }
  }
  /* enter given ideals ------------------------------------------*/
  i = maxrk;
  k = 0;
  for (j=0;j<length;j++)
  {
    if (arg[j]!=NULL)