RingElem CommonDenom(ConstRefRingElem f)
{
if (!IsPolyRing(owner(f)))
CoCoA_ERROR(ERR::NotElemPolyRing, "CommonDenom(f)");
const PolyRing Qx = owner(f);
const ring Q = CoeffRing(Qx);
if (!IsFractionField(Q))
CoCoA_ERROR(ERR::NotElemFrF, "CoeffRing inside CommonDenom(f)");
const ring R = BaseRing(Q);
if (!IsTrueGCDDomain(R))
CoCoA_ERROR(ERR::NotTrueGCDDomain, "BaseRing of CoeffRing inside CommonDenom(f)");
// if (IsField(R)) // see documentation (Bugs section)
// CoCoA_ERROR(ERR::NotTrueGCDDomain, "content(f)");
if (IsZero(f)) return one(R);
RingElem ans(R);
Qx->myCommonDenom(raw(ans), raw(f));
return ans;
}
