Function init4ext

factory/facFqBivar.cc:7659–7710

findMinPoly

#ifdef HAVE_NTL // findMinPoly
ExtensionInfo
init4ext (const ExtensionInfo& info, const CanonicalForm& evaluation,
          int& degMipo
         )
{
  bool GF= (CFFactory::gettype() == GaloisFieldDomain);
  Variable alpha= info.getAlpha();
  if (GF)
  {
    degMipo= getGFDegree();
    CanonicalForm GFMipo= gf_mipo;
    setCharacteristic (getCharacteristic());
    GFMipo.mapinto();
    alpha= rootOf (GFMipo);
    setCharacteristic (getCharacteristic(), degMipo, info.getGFName());
  }
  else
  {
    alpha= info.getAlpha();
    degMipo= degree (getMipo (alpha));
  }

  Variable gamma;
  CanonicalForm primElemAlpha, imPrimElemAlpha;
  if ((!GF && evaluation != alpha) || (GF && evaluation != getGFGenerator()))
  {
    CanonicalForm bufEvaluation;
    if (GF)
    {
      setCharacteristic (getCharacteristic());
      bufEvaluation= GF2FalphaRep (evaluation, alpha);
    }
    else
      bufEvaluation= evaluation;
    CanonicalForm mipo= findMinPoly (bufEvaluation, alpha);
    gamma= rootOf (mipo);
    Variable V_buf;
    bool fail= false;
    primElemAlpha= primitiveElement (alpha, V_buf, fail);
    imPrimElemAlpha= map (primElemAlpha, alpha, bufEvaluation, gamma);

    if (GF)
      setCharacteristic (getCharacteristic(), degMipo, info.getGFName());
  }
  else
    gamma= alpha;
  ExtensionInfo info2= ExtensionInfo (alpha, gamma, primElemAlpha,
                                      imPrimElemAlpha, 1, info.getGFName(), true
                                     );

  return info2;
}
#endif

#ifdef HAVE_NTL // extSieveSmallFactors,...