void SqrTrunc(zz_pX& x, const zz_pX& a, long n)
{
   if (n < 0) Error("SqrTrunc: bad args");

   if (deg(a) <= NTL_zz_pX_MUL_CROSSOVER)
      PlainSqrTrunc(x, a, n);
   else
      FFTSqrTrunc(x, a, n);
}
void SqrTrunc(ZZ_pX& x, const ZZ_pX& a, long n)
{
   if (n < 0) LogicError("SqrTrunc: bad args");

   if (deg(a) <= NTL_ZZ_pX_FFT_CROSSOVER)
      PlainSqrTrunc(x, a, n);
   else
      FFTSqrTrunc(x, a, n);
}