source: git/Singular/polys1.cc @ 50cbdc

/****************************************
*  Computer Algebra System SINGULAR     *
****************************************/
/* $Id: polys1.cc,v 1.68 2001-08-27 14:47:33 Singular Exp $ */

/*
* ABSTRACT - all basic methods to manipulate polynomials:
* independent of representation
*/

/* includes */
#include <string.h>
#include "mod2.h"
#include "structs.h"
#include "tok.h"
#include "numbers.h"
#include "ffields.h"
#include "omalloc.h"
#include "febase.h"
#include "weight.h"
#include "intvec.h"
#include "longalg.h"
#include "ring.h"
#include "ideals.h"
#include "polys.h"
//#include "ipid.h"
#ifdef HAVE_FACTORY
#include "clapsing.h"
#endif

/*-------- several access procedures to monomials -------------------- */
/*
* the module weights for std
*/
static pFDegProc pOldFDeg;
static pLDegProc pOldLDeg;
static intvec * pModW;
static BOOLEAN pOldLexOrder;

static long pModDeg(poly p, ring r = currRing)
{
  return pOldFDeg(p, r)+(*pModW)[p_GetComp(p, r)-1];
}

void pSetModDeg(intvec *w)
{
  if (w!=NULL)
  {
    pModW = w;
    pOldFDeg = pFDeg;
    pOldLDeg = pLDeg;
    pOldLexOrder = pLexOrder;
    pSetDegProcs(pModDeg);
    pLexOrder = TRUE;
  }
  else
  {
    pModW = NULL;
    pRestoreDegProcs(pOldFDeg, pOldLDeg);
    pLexOrder = pOldLexOrder;
  }
}


/*2
* subtract p2 from p1, p1 and p2 are destroyed
* do not put attention on speed: the procedure is only used in the interpreter
*/
poly pSub(poly p1, poly p2)
{
  return pAdd(p1, pNeg(p2));
}

/*3
*  create binomial coef.
*/
static number* pnBin(int exp)
{
  int e, i, h;
  number x, y, *bin=NULL;

  x = nInit(exp);
  if (nIsZero(x))
  {
    nDelete(&x);
    return bin;
  }
  h = (exp >> 1) + 1;
  bin = (number *)omAlloc0(h*sizeof(number));
  bin[1] = x;
  if (exp < 4)
    return bin;
  i = exp - 1;
  for (e=2; e<h; e++)
  {
//    if(!nIsZero(bin[e-1]))
//    {
      x = nInit(i);
      i--;
      y = nMult(x,bin[e-1]);
      nDelete(&x);
      x = nInit(e);
      bin[e] = nIntDiv(y,x);
      nDelete(&x);
      nDelete(&y);
//    }
//    else
//    {
//      bin[e] = nInit(binom(exp,e));
//    }
  }
  return bin;
}

static void pnFreeBin(number *bin, int exp)
{
  int e, h = (exp >> 1) + 1;

  if (bin[1] != NULL)
  {
    for (e=1; e<h; e++)
      nDelete(&(bin[e]));
  }
  omFreeSize((ADDRESS)bin, h*sizeof(number));
}

/*3
* compute for a monomial m
* the power m^exp, exp > 1
* destroys p
*/
static poly pMonPower(poly p, int exp)
{
  int i;

  if(!nIsOne(pGetCoeff(p)))
  {
    number x, y;
    y = pGetCoeff(p);
    nPower(y,exp,&x);
    nDelete(&y);
    pSetCoeff0(p,x);
  }
  for (i=pVariables; i!=0; i--)
  {
    pMultExp(p,i, exp);
  }
  pSetm(p);
  return p;
}

/*3
* compute for monomials p*q
* destroys p, keeps q
*/
static void pMonMult(poly p, poly q)
{
  number x, y;
  int i;

  y = pGetCoeff(p);
  x = nMult(y,pGetCoeff(q));
  nDelete(&y);
  pSetCoeff0(p,x);
  //for (i=pVariables; i!=0; i--)
  //{
  //  pAddExp(p,i, pGetExp(q,i));
  //}
  //p->Order += q->Order;
  pExpVectorAdd(p,q);
}

/*3
* compute for monomials p*q
* keeps p, q
*/
static poly pMonMultC(poly p, poly q)
{
  number x;
  int i;
  poly r = pInit();

  x = nMult(pGetCoeff(p),pGetCoeff(q));
  pSetCoeff0(r,x);
  pExpVectorSum(r,p, q);
  return r;
}

/*
*  compute for a poly p = head+tail, tail is monomial
*          (head + tail)^exp, exp > 1
*          with binomial coef.
*/
static poly pTwoMonPower(poly p, int exp)
{
  int eh, e, al;
  poly *a;
  poly tail, b, res, h;
  number x;
  number *bin = pnBin(exp);

  tail = pNext(p);
  if (bin == NULL)
  {
    pMonPower(p,exp);
    pMonPower(tail,exp);
#ifdef PDEBUG
    pTest(p);
#endif
    return p;
  }
  eh = exp >> 1;
  al = (exp + 1) * sizeof(poly);
  a = (poly *)omAlloc(al);
  a[1] = p;
  for (e=1; e<exp; e++)
  {
    a[e+1] = pMonMultC(a[e],p);
  }
  res = a[exp];
  b = pHead(tail);
  for (e=exp-1; e>eh; e--)
  {
    h = a[e];
    x = nMult(bin[exp-e],pGetCoeff(h));
    pSetCoeff(h,x);
    pMonMult(h,b);
    res = pNext(res) = h;
    pMonMult(b,tail);
  }
  for (e=eh; e!=0; e--)
  {
    h = a[e];
    x = nMult(bin[e],pGetCoeff(h));
    pSetCoeff(h,x);
    pMonMult(h,b);
    res = pNext(res) = h;
    pMonMult(b,tail);
  }
  pDeleteLm(&tail);
  pNext(res) = b;
  pNext(b) = NULL;
  res = a[exp];
  omFreeSize((ADDRESS)a, al);
  pnFreeBin(bin, exp);
//  tail=res;
// while((tail!=NULL)&&(pNext(tail)!=NULL))
// {
//   if(nIsZero(pGetCoeff(pNext(tail))))
//   {
//     pDeleteLm(&pNext(tail));
//   }
//   else
//     pIter(tail);
// }
#ifdef PDEBUG
  pTest(res);
#endif
  return res;
}

static poly pPow(poly p, int i)
{
  poly rc = pCopy(p);
  i -= 2;
  do
  {
    rc = pMult(rc,pCopy(p));
    pNormalize(rc);
    i--;
  }
  while (i != 0);
  return pMult(rc,p);
}

/*2
* returns the i-th power of p
* p will be destroyed
*/
poly pPower(poly p, int i)
{
  poly rc=NULL;

  if (i==0)
  {
    pDelete(&p);
    return pOne();
  }

  if(p!=NULL)
  {
    if ( (i > 0) && ((unsigned long ) i > (currRing->bitmask)))
    {
      Werror("exponent %d is too large, max. is %d",i,currRing->bitmask);
      return NULL;
    }
    switch (i)
    {
// cannot happen, see above
//      case 0:
//      {
//        rc=pOne();
//#ifdef DRING
//        if ((pDRING) && (pdDFlag(p)==1))
//        {
//          pdSetDFlag(rc,1);
//        }
//#endif
//        pDelete(&p);
//        break;
//      }
      case 1:
        rc=p;
        break;
      case 2:
        rc=pMult(pCopy(p),p);
        break;
      default:
        if (i < 0)
        {
          pDelete(&p);
          return NULL;
        }
        else
        {
          rc = pNext(p);
          if (rc == NULL)
            return pMonPower(p,i);
          /* else: binom ?*/
          int char_p=rChar(currRing);
          if (pNext(rc) != NULL)
            return pPow(p,i);
          if ((char_p==0) || (i<=char_p))
            return pTwoMonPower(p,i);
          poly p_p=pTwoMonPower(pCopy(p),char_p);
          return pMult(pPower(p,i-char_p),p_p);
        }
      /*end default:*/
    }
  }
  return rc;
}

/*2
* returns the partial differentiate of a by the k-th variable
* does not destroy the input
*/
poly pDiff(poly a, int k)
{
  poly res, f, last;
  number t;

  last = res = NULL;
  while (a!=NULL)
  {
    if (pGetExp(a,k)!=0)
    {
      f = pLmInit(a);
      t = nInit(pGetExp(a,k));
      pSetCoeff0(f,nMult(t,pGetCoeff(a)));
      nDelete(&t);
      if (nIsZero(pGetCoeff(f)))
        pDeleteLm(&f);
      else
      {
        pDecrExp(f,k);
        pSetm(f);
        if (res==NULL)
        {
          res=last=f;
        }
        else
        {
          pNext(last)=f;
          last=f;
        }
      }
    }
    pIter(a);
  }
  return res;
}

static poly pDiffOpM(poly a, poly b,BOOLEAN multiply)
{
  int i,j,s;
  number n,h,hh;
  poly p=pOne();
  n=nMult(pGetCoeff(a),pGetCoeff(b));
  for(i=pVariables;i>0;i--)
  {
    s=pGetExp(b,i);
    if (s<pGetExp(a,i))
    {
      nDelete(&n);
      pDeleteLm(&p);
      return NULL;
    }
    if (multiply)
    {
      for(j=pGetExp(a,i); j>0;j--)
      {
        h = nInit(s);
        hh=nMult(n,h);
        nDelete(&h);
        nDelete(&n);
        n=hh;
        s--;
      }
      pSetExp(p,i,s);
    }
    else
    {
      pSetExp(p,i,s-pGetExp(a,i));
    }
  }
  pSetm(p);
  /*if (multiply)*/ pSetCoeff(p,n);
  return p;
}

poly pDiffOp(poly a, poly b,BOOLEAN multiply)
{
  poly result=NULL;
  poly h;
  for(;a!=NULL;pIter(a))
  {
    for(h=b;h!=NULL;pIter(h))
    {
      result=pAdd(result,pDiffOpM(a,h,multiply));
    }
  }
  return result;
}


void pSplit(poly p, poly *h)
{
  *h=pNext(p);
  pNext(p)=NULL;
}



int pMaxCompProc(poly p)
{
  return pMaxComp(p);
}

/*2
* handle memory request for sets of polynomials (ideals)
* l is the length of *p, increment is the difference (may be negative)
*/
void pEnlargeSet(polyset *p, int l, int increment)
{
  int i;
  polyset h;

  h=(polyset)omReallocSize((poly*)*p,l*sizeof(poly),(l+increment)*sizeof(poly));
  if (increment>0)
  {
    //for (i=l; i<l+increment; i++)
    //  h[i]=NULL;
    memset(&(h[l]),0,increment*sizeof(poly));
  }
  *p=h;
}

void pContent(poly ph)
{
  number h,d;
  poly p;

  if(TEST_OPT_CONTENTSB) return;
  if(pNext(ph)==NULL)
  {
    pSetCoeff(ph,nInit(1));
  }
  else
  {
    nNormalize(pGetCoeff(ph));
    if(!nGreaterZero(pGetCoeff(ph))) ph = pNeg(ph);
    h=nCopy(pGetCoeff(ph));
    p = pNext(ph);
    while (p!=NULL)
    {
      nNormalize(pGetCoeff(p));
      d=nGcd(h,pGetCoeff(p),currRing);
      nDelete(&h);
      h = d;
      if(nIsOne(h))
      {
        break;
      }
      pIter(p);
    }
    p = ph;
    //number tmp;
    if(!nIsOne(h))
    {
      while (p!=NULL)
      {
        //d = nDiv(pGetCoeff(p),h);
        //tmp = nIntDiv(pGetCoeff(p),h);
        //if (!nEqual(d,tmp))
        //{
        //  StringSetS("** div0:");nWrite(pGetCoeff(p));StringAppendS("/");
        //  nWrite(h);StringAppendS("=");nWrite(d);StringAppendS(" int:");
        //  nWrite(tmp);Print(StringAppendS("\n"));
        //}
        //nDelete(&tmp);
        d = nIntDiv(pGetCoeff(p),h);
        pSetCoeff(p,d);
        pIter(p);
      }
    }
    nDelete(&h);
#ifdef HAVE_FACTORY
    if ( (nGetChar() == 1) || (nGetChar() < 0) ) /* Q[a],Q(a),Zp[a],Z/p(a) */
    {
      singclap_divide_content(ph);
      if(!nGreaterZero(pGetCoeff(ph))) ph = pNeg(ph);
    }
#endif
  }
}

//void pContent(poly ph)
//{
//  number h,d;
//  poly p;
//
//  p = ph;
//  if(pNext(p)==NULL)
//  {
//    pSetCoeff(p,nInit(1));
//  }
//  else
//  {
//#ifdef PDEBUG
//    if (!pTest(p)) return;
//#endif
//    nNormalize(pGetCoeff(p));
//    if(!nGreaterZero(pGetCoeff(ph)))
//    {
//      ph = pNeg(ph);
//      nNormalize(pGetCoeff(p));
//    }
//    h=pGetCoeff(p);
//    pIter(p);
//    while (p!=NULL)
//    {
//      nNormalize(pGetCoeff(p));
//      if (nGreater(h,pGetCoeff(p))) h=pGetCoeff(p);
//      pIter(p);
//    }
//    h=nCopy(h);
//    p=ph;
//    while (p!=NULL)
//    {
//      d=nGcd(h,pGetCoeff(p));
//      nDelete(&h);
//      h = d;
//      if(nIsOne(h))
//      {
//        break;
//      }
//      pIter(p);
//    }
//    p = ph;
//    //number tmp;
//    if(!nIsOne(h))
//    {
//      while (p!=NULL)
//      {
//        d = nIntDiv(pGetCoeff(p),h);
//        pSetCoeff(p,d);
//        pIter(p);
//      }
//    }
//    nDelete(&h);
//#ifdef HAVE_FACTORY
//    if ( (nGetChar() == 1) || (nGetChar() < 0) ) /* Q[a],Q(a),Zp[a],Z/p(a) */
//    {
//      pTest(ph);
//      singclap_divide_content(ph);
//      pTest(ph);
//    }
//#endif
//  }
//}
void p_Content(poly ph, ring r)
{
  number h,d;
  poly p;

  if(pNext(ph)==NULL)
  {
    pSetCoeff(ph,n_Init(1,r));
  }
  else
  {
    n_Normalize(pGetCoeff(ph),r);
    if(!n_GreaterZero(pGetCoeff(ph),r)) ph = p_Neg(ph,r);
    h=n_Copy(pGetCoeff(ph),r);
    p = pNext(ph);
    while (p!=NULL)
    {
      n_Normalize(pGetCoeff(p),r);
      d=n_Gcd(h,pGetCoeff(p),r);
      n_Delete(&h,r);
      h = d;
      if(n_IsOne(h,r))
      {
        break;
      }
      pIter(p);
    }
    p = ph;
    //number tmp;
    if(!n_IsOne(h,r))
    {
      while (p!=NULL)
      {
        //d = nDiv(pGetCoeff(p),h);
        //tmp = nIntDiv(pGetCoeff(p),h);
        //if (!nEqual(d,tmp))
        //{
        //  StringSetS("** div0:");nWrite(pGetCoeff(p));StringAppendS("/");
        //  nWrite(h);StringAppendS("=");nWrite(d);StringAppendS(" int:");
        //  nWrite(tmp);Print(StringAppendS("\n"));
        //}
        //nDelete(&tmp);
        d = n_IntDiv(pGetCoeff(p),h,r);
        p_SetCoeff(p,d,r);
        pIter(p);
      }
    }
    n_Delete(&h,r);
#ifdef HAVE_FACTORY
    //if ( (nGetChar() == 1) || (nGetChar() < 0) ) /* Q[a],Q(a),Zp[a],Z/p(a) */
    //{
    //  singclap_divide_content(ph);
    //  if(!nGreaterZero(pGetCoeff(ph))) ph = pNeg(ph);
    //}
#endif
  }
}

void pCleardenom(poly ph)
{
  number d, h;
  poly p;

  p = ph;
  if(pNext(p)==NULL)
  {
    if (TEST_OPT_CONTENTSB)
    {
      number n=nGetDenom(pGetCoeff(p));
      if (!nIsOne(n))
      {
        number nn=nMult(pGetCoeff(p),n);
        nNormalize(nn);
        pSetCoeff(p,nn);
      }
      nDelete(&n);
    }
    else
      pSetCoeff(p,nInit(1));
  }
  else
  {
    h = nInit(1);
    while (p!=NULL)
    {
      nNormalize(pGetCoeff(p));
      d=nLcm(h,pGetCoeff(p),currRing);
      nDelete(&h);
      h=d;
      pIter(p);
    }
    /* contains the 1/lcm of all denominators */
    if(!nIsOne(h))
    {
      p = ph;
      while (p!=NULL)
      {
        /* should be:
        * number hh;
        * nGetDenom(p->coef,&hh);
        * nMult(&h,&hh,&d);
        * nNormalize(d);
        * nDelete(&hh);
        * nMult(d,p->coef,&hh);
        * nDelete(&d);
        * nDelete(&(p->coef));
        * p->coef =hh;
        */
        d=nMult(h,pGetCoeff(p));
        nNormalize(d);
        pSetCoeff(p,d);
        pIter(p);
      }
      nDelete(&h);
      if (nGetChar()==1)
      {
        loop
        {
          h = nInit(1);
          p=ph;
          while (p!=NULL)
          {
            d=nLcm(h,pGetCoeff(p),currRing);
            nDelete(&h);
            h=d;
            pIter(p);
          }
          /* contains the 1/lcm of all denominators */
          if(!nIsOne(h))
          {
            p = ph;
            while (p!=NULL)
            {
              /* should be:
              * number hh;
              * nGetDenom(p->coef,&hh);
              * nMult(&h,&hh,&d);
              * nNormalize(d);
              * nDelete(&hh);
              * nMult(d,p->coef,&hh);
              * nDelete(&d);
              * nDelete(&(p->coef));
              * p->coef =hh;
              */
              d=nMult(h,pGetCoeff(p));
              nNormalize(d);
              pSetCoeff(p,d);
              pIter(p);
            }
            nDelete(&h);
          }
          else
          {
            nDelete(&h);
            break;
          }
        }
      }
    }
    if (h!=NULL) nDelete(&h);
    pContent(ph);
  }
}

/*2
*tests if p is homogeneous with respect to the actual weigths
*/
BOOLEAN pIsHomogeneous (poly p)
{
  poly qp=p;
  int o;

  if ((p == NULL) || (pNext(p) == NULL)) return TRUE;
  pFDegProc d=(pLexOrder ? pTotaldegree : pFDeg );
  o = d(p);
  do
  {
    if (d(qp) != o) return FALSE;
    pIter(qp);
  }
  while (qp != NULL);
  return TRUE;
}

// orders monoms of poly using merge sort (ususally faster than
// insertion sort). ASSUMES that pSetm was performed on monoms
poly pOrdPolyMerge(poly p)
{
  poly qq,pp,result=NULL;

  if (p == NULL) return NULL;

  loop
  {
    qq = p;
    loop
    {
      if (pNext(p) == NULL)
      {
        result=pAdd(result, qq);
        pTest(result);
        return result;
      }
      if (pLmCmp(p,pNext(p)) != 1)
      {
        pp = p;
        pIter(p);
        pNext(pp) = NULL;
        result = pAdd(result, qq);
        break;
      }
      pIter(p);
    }
  }
}

// orders monoms of poly using insertion sort, performs pSetm on each monom
poly pOrdPolyInsertSetm(poly p)
{
  poly qq,result = NULL;

#if 0
  while (p != NULL)
  {
    qq = p;
    pIter(p);
    qq->next = NULL;
    pSetm(qq);
    result = pAdd(result,qq);
    pTest(result);
  }
#else
  while (p != NULL)
  {
    qq = p;
    pIter(p);
    qq->next = result;
    result = qq;
    pSetm(qq);
  }
  p = result;
  result = NULL;
  while (p != NULL)
  {
    qq = p;
    pIter(p);
    qq->next = NULL;
    result = pAdd(result, qq);
  }
  pTest(result);
#endif
  return result;
}

/*2
*returns a re-ordered copy of a polynomial, with permutation of the variables
*/
poly pPermPoly (poly p, int * perm, ring oldRing, nMapFunc nMap,
   int *par_perm, int OldPar)
{
  int OldpVariables = oldRing->N;
  poly result = NULL;
  poly result_last = NULL;
  poly aq=NULL; /* the map coefficient */
  poly qq; /* the mapped monomial */

  while (p != NULL)
  {
    if ((OldPar==0)||(rField_is_GF(oldRing)))
    {
      qq = pInit();
      number n=nMap(pGetCoeff(p));
      if ((currRing->minpoly!=NULL)
      && ((rField_is_Zp_a()) || (rField_is_Q_a())))
      {
        nNormalize(n);
      }
      pGetCoeff(qq)=n;
    // coef may be zero:  pTest(qq);
    }
    else
    {
      qq=pOne();
      aq=naPermNumber(pGetCoeff(p),par_perm,OldPar, oldRing);
      if ((currRing->minpoly!=NULL)
      && ((rField_is_Zp_a()) || (rField_is_Q_a())))
      {
        poly tmp=aq;
        while (tmp!=NULL)
        {
          number n=pGetCoeff(tmp);
          nNormalize(n);
          pGetCoeff(tmp)=n;
          pIter(tmp);
        }
      }
      pTest(aq);
    }
    pSetComp(qq, p_GetComp(p,oldRing));
    if (nIsZero(pGetCoeff(qq)))
    {
      pDeleteLm(&qq);
    }
    else
    {
      int i;
      int mapped_to_par=0;
      for(i=1; i<=OldpVariables; i++)
      {
        int e=p_GetExp(p,i,oldRing);
        if (e!=0)
        {
          if (perm==NULL)
          {
            pSetExp(qq,i, e);
          }
          else if (perm[i]>0)
            pAddExp(qq,perm[i], e/*p_GetExp( p,i,oldRing)*/);
          else if (perm[i]<0)
          {
            if (rField_is_GF())
            {
              number c=pGetCoeff(qq);
              number ee=nfPar(1);
              number eee;nfPower(ee,e,&eee); //nfDelete(ee,currRing);
              ee=nfMult(c,eee);
              //nfDelete(c,currRing);nfDelete(eee,currRing);
              pSetCoeff0(qq,ee);
            }
            else
            {
              lnumber c=(lnumber)pGetCoeff(qq);
              napAddExp(c->z,-perm[i],e/*p_GetExp( p,i,oldRing)*/);
              mapped_to_par=1;
            }
          }
          else
          {
            /* this variable maps to 0 !*/
            pDeleteLm(&qq);
            break;
          }
        }
      }
      if (mapped_to_par
      && (currRing->minpoly!=NULL))
      {
        number n=pGetCoeff(qq);
        nNormalize(n);
        pGetCoeff(qq)=n;
      }
    }
    pIter(p);
#if 1
    if (qq!=NULL)
    {
      pSetm(qq);
      pTest(aq);
      pTest(qq);
      if (aq!=NULL) qq=pMult(aq,qq);
      aq = qq;
      while (pNext(aq) != NULL) pIter(aq);
      if (result_last==NULL)
      {
        result=qq;
      }
      else
      {
        pNext(result_last)=qq;
      }
      result_last=aq;
      aq = NULL;
    }
    else if (aq!=NULL)
    {
      pDelete(&aq);
    }
  }
  result=pSortAdd(result);
#else
  //  if (qq!=NULL)
  //  {
  //    pSetm(qq);
  //    pTest(qq);
  //    pTest(aq);
  //    if (aq!=NULL) qq=pMult(aq,qq);
  //    aq = qq;
  //    while (pNext(aq) != NULL) pIter(aq);
  //    pNext(aq) = result;
  //    aq = NULL;
  //    result = qq;
  //  }
  //  else if (aq!=NULL)
  //  {
  //    pDelete(&aq);
  //  }
  //}
  //p = result;
  //result = NULL;
  //while (p != NULL)
  //{
  //  qq = p;
  //  pIter(p);
  //  qq->next = NULL;
  //  result = pAdd(result, qq);
  //}
#endif
  pTest(result);
  return result;
}

#if 0
/*2
*returns a re-ordered copy of a polynomial, with permutation of the variables
*/
poly p_PermPoly (poly p, int * perm, ring oldRing,
   int *par_perm, int OldPar, ring newRing)
{
  int OldpVariables = oldRing->N;
  poly result = NULL;
  poly result_last = NULL;
  poly aq=NULL; /* the map coefficient */
  poly qq; /* the mapped monomial */

  while (p != NULL)
  {
    if (OldPar==0)
    {
      qq = pInit();
      number n=newRing->cf->nMap(pGetCoeff(p));
      if ((newRing->minpoly!=NULL)
      && ((rField_is_Zp_a(newRing)) || (rField_is_Q_a(newRing))))
      {
        newRing->cf->nNormalize(n);
      }
      pGetCoeff(qq)=n;
    // coef may be zero:  pTest(qq);
    }
    else
    {
      qq=p_ISet(1, newRing);
      aq=naPermNumber(pGetCoeff(p),par_perm,OldPar, oldRing);
      if ((newRing->minpoly!=NULL)
      && ((rField_is_Zp_a(newRing)) || (rField_is_Q_a(newRing))))
      {
        poly tmp=aq;
        while (tmp!=NULL)
        {
          number n=pGetCoeff(tmp);
          newRing->cf->nNormalize(n);
          pGetCoeff(tmp)=n;
          pIter(tmp);
        }
      }
      //pTest(aq);
    }
    p_SetComp(qq, p_GetComp(p,oldRing), newRing);
    if (newRing->cf->nIsZero(pGetCoeff(qq)))
    {
      p_DeleteLm(&qq, newRing);
    }
    else
    {
      int i;
      int mapped_to_par=0;
      for(i=1; i<=OldpVariables; i++)
      {
        int e=p_GetExp(p,i,oldRing);
        if (e!=0)
        {
          if (perm==NULL)
          {
            p_SetExp(qq,i, e, newRing);
          }
          else if (perm[i]>0)
            p_AddExp(qq,perm[i], e/*p_GetExp( p,i,oldRing)*/, newRing);
          else if (perm[i]<0)
          {
            lnumber c=(lnumber)pGetCoeff(qq);
            napAddExp(c->z,-perm[i],e/*p_GetExp( p,i,oldRing)*/);
            mapped_to_par=1;
          }
          else
          {
            /* this variable maps to 0 !*/
            p_DeleteLm(&qq, newRing);
            break;
          }
        }
      }
      if (mapped_to_par
      && (newRing->minpoly!=NULL))
      {
        number n=pGetCoeff(qq);
        newRing->cf->nNormalize(n);
        pGetCoeff(qq)=n;
      }
    }
    pIter(p);
    if (qq!=NULL)
    {
      p_Setm(qq, newRing);
      //pTest(aq);
      //pTest(qq);
      if (aq!=NULL) qq=pMult(aq,qq);
      aq = qq;
      while (pNext(aq) != NULL) pIter(aq);
      if (result_last==NULL)
      {
        result=qq;
      }
      else
      {
        pNext(result_last)=qq;
      }
      result_last=aq;
      aq = NULL;
    }
    else if (aq!=NULL)
    {
      p_Delete(&aq, newRing);
    }
  }
  result=pOrdPolyMerge(result);
  //pTest(result);
  return result;
}
#endif

poly ppJet(poly p, int m)
{
  poly r=NULL;
  poly t=NULL;

  while (p!=NULL)
  {
    if (pTotaldegree(p)<=m)
    {
      if (r==NULL)
        r=pHead(p);
      else
      if (t==NULL)
      {
        pNext(r)=pHead(p);
        t=pNext(r);
      }
      else
      {
        pNext(t)=pHead(p);
        pIter(t);
      }
    }
    pIter(p);
  }
  return r;
}

poly pJet(poly p, int m)
{
  poly t=NULL;

  while((p!=NULL) && (pTotaldegree(p)>m)) pLmDelete(&p);
  if (p==NULL) return NULL;
  poly r=p;
  while (pNext(p)!=NULL)
  {
    if (pTotaldegree(pNext(p))>m)
    {
      pLmDelete(&pNext(p));
    }
    else
      pIter(p);
  }
  return r;
}

poly ppJetW(poly p, int m, short *w)
{
  poly r=NULL;
  poly t=NULL;
  while (p!=NULL)
  {
    if (totaldegreeWecart_IV(p,currRing,w)<=m)
    {
      if (r==NULL)
        r=pHead(p);
      else
      if (t==NULL)
      {
        pNext(r)=pHead(p);
        t=pNext(r);
      }
      else
      {
        pNext(t)=pHead(p);
        pIter(t);
      }
    }
    pIter(p);
  }
  return r;
}

poly pJetW(poly p, int m, short *w)
{
  poly t=NULL;
  while((p!=NULL) && (totaldegreeWecart_IV(p,currRing,w)>m)) pLmDelete(&p);
  if (p==NULL) return NULL;
  poly r=p;
  while (pNext(p)!=NULL)
  {
    if (totaldegreeWecart_IV(pNext(p),currRing,w)>m)
    {
      pLmDelete(&pNext(p));
    }
    else
      pIter(p);
  }
  return r;
}

int pMinDeg(poly p,intvec *w=NULL)
{
  if(p==NULL)
    return -1;
  int d=-1;
  while(p!=NULL)
  {
    int d0=0;
    for(int j=0;j<pVariables;j++)
      if(w==NULL||j>=w->length())
        d0+=pGetExp(p,j+1);
      else
        d0+=(*w)[j]*pGetExp(p,j+1);
    if(d0<d||d==-1)
      d=d0;
    pIter(p);
  }
  return d;
}

poly pSeries(int n,poly p,poly u, intvec *w)
{
  short *ww=iv2array(w);
  if(p!=NULL)
  {
    if(u==NULL)
      p=pJetW(p,n,ww);
    else
      p=pJetW(pMult(p,pInvers(n-pMinDeg(p,w),u,w)),n,ww);
  }
  omFreeSize((ADDRESS)ww,(pVariables+1)*sizeof(short));
  return p;
}

poly pInvers(int n,poly u,intvec *w)
{
  short *ww=iv2array(w);
  if(n<0)
    return NULL;
  number u0=nInvers(pGetCoeff(u));
  poly v=pNSet(u0);
  if(n==0)
    return v;
  poly u1=pJetW(pSub(pOne(),pMult_nn(u,u0)),n,ww);
  if(u1==NULL)
    return v;
  poly v1=pMult_nn(pCopy(u1),u0);
  v=pAdd(v,pCopy(v1));
  for(int i=n/pMinDeg(u1,w);i>1;i--)
  {
    v1=pJetW(pMult(v1,pCopy(u1)),n,ww);
    v=pAdd(v,pCopy(v1));
  }
  pDelete(&u1);
  pDelete(&v1);
  omFreeSize((ADDRESS)ww,(pVariables+1)*sizeof(short));
  return v;
}

int pDegW(poly p, short *w)
{
  int r=0;

  while (p!=NULL)
  {
    r=max(r, totaldegreeWecart_IV(p,currRing,w));
    pIter(p);
  }
  return r;
}

/*-----------type conversions ----------------------------*/
/*2
* input: a set of polys (len elements: p[0]..p[len-1])
* output: a vector
* p will not be changed
*/
poly  pPolys2Vec(polyset p, int len)
{
  poly v=NULL;
  poly h;
  int i;

  for (i=len-1; i>=0; i--)
  {
    if (p[i])
    {
      h=pCopy(p[i]);
      pSetCompP(h,i+1);
      v=pAdd(v,h);
    }
  }
 return v;
}

/*2
* convert a vector to a set of polys,
* allocates the polyset, (entries 0..(*len)-1)
* the vector will not be changed
*/
void  pVec2Polys(poly v, polyset *p, int *len)
{
  poly h;
  int k;

  *len=pMaxComp(v);
  if (*len==0) *len=1;
  *p=(polyset)omAlloc0((*len)*sizeof(poly));
  while (v!=NULL)
  {
    h=pHead(v);
    k=pGetComp(h);
    pSetComp(h,0);
    (*p)[k-1]=pAdd((*p)[k-1],h);
    pIter(v);
  }
}

int pVar(poly m)
{
  if (m==NULL) return 0;
  if (pNext(m)!=NULL) return 0;
  int i,e=0;
  for (i=pVariables; i>0; i--)
  {
    if (pGetExp(m,i)==1)
    {
      if (e==0) e=i;
      else return 0;
    }
  }
  return e;
}

/*----------utilities for syzygies--------------*/
//BOOLEAN   pVectorHasUnitM(poly p, int * k)
//{
//  while (p!=NULL)
//  {
//    if (pLmIsConstantComp(p))
//    {
//      *k = pGetComp(p);
//      return TRUE;
//    }
//    else pIter(p);
//  }
//  return FALSE;
//}

BOOLEAN   pVectorHasUnitB(poly p, int * k)
{
  poly q=p,qq;
  int i;

  while (q!=NULL)
  {
    if (pLmIsConstantComp(q))
    {
      i = pGetComp(q);
      qq = p;
      while ((qq != q) && (pGetComp(qq) != i)) pIter(qq);
      if (qq == q)
      {
        *k = i;
        return TRUE;
      }
      else
        pIter(q);
    }
    else pIter(q);
  }
  return FALSE;
}

void   pVectorHasUnit(poly p, int * k, int * len)
{
  poly q=p,qq;
  int i,j=0;

  *len = 0;
  while (q!=NULL)
  {
    if (pLmIsConstantComp(q))
    {
      i = pGetComp(q);
      qq = p;
      while ((qq != q) && (pGetComp(qq) != i)) pIter(qq);
      if (qq == q)
      {
       j = 0;
       while (qq!=NULL)
       {
         if (pGetComp(qq)==i) j++;
        pIter(qq);
       }
       if ((*len == 0) || (j<*len))
       {
         *len = j;
         *k = i;
       }
      }
    }
    pIter(q);
  }
}

/*2
* returns TRUE if p1 = p2
*/
BOOLEAN pEqualPolys(poly p1,poly p2)
{
  while ((p1 != NULL) && (p2 != NULL))
  {
    if (! pLmEqual(p1, p2))
      return FALSE;
    if (! nEqual(pGetCoeff(p1), pGetCoeff(p2)))
      return FALSE;
    pIter(p1);
    pIter(p2);
  }
  return (p1==p2);
}

/*2
*returns TRUE if p1 is a skalar multiple of p2
*assume p1 != NULL and p2 != NULL
*/
BOOLEAN pComparePolys(poly p1,poly p2)
{
  number n,nn;
  int i;
  pAssume(p1 != NULL && p2 != NULL);

  if (!pLmEqual(p1,p2)) //compare leading mons
      return FALSE;
  if ((pNext(p1)==NULL) && (pNext(p2)!=NULL))
     return FALSE;
  if ((pNext(p2)==NULL) && (pNext(p1)!=NULL))
     return FALSE;
  if (pLength(p1) != pLength(p2))
    return FALSE;
  n=nDiv(pGetCoeff(p1),pGetCoeff(p2));
  while ((p1 != NULL) /*&& (p2 != NULL)*/)
  {
    if ( ! pLmEqual(p1, p2))
    {
        nDelete(&n);
        return FALSE;
    }
    if (!nEqual(pGetCoeff(p1),nn=nMult(pGetCoeff(p2),n)))
    {
      nDelete(&n);
      nDelete(&nn);
      return FALSE;
    }
    nDelete(&nn);
    pIter(p1);
    pIter(p2);
  }
  nDelete(&n);
  return TRUE;
}