power() [2/2]

ring_elem LocalRing::power ( const ring_elem f, mpz_srcptr n ) const

virtual

Exponentiation. This is the default function, if a class doesn't define this.

Reimplemented from Ring.

Definition at line 570 of file localring.cpp.

{
  const local_elem *f = a.get_local_elem();
  ring_elem top, bottom;
  if (mpz_sgn(n) >= 0)
    {
      top = mRing->power(f->numer, n);
      bottom = mRing->power(f->denom, n);
 
      if (mRing->is_zero(bottom)) return set_non_unit_frac(f->denom);
    }
  else
    {
      mpz_t negative_n;
      mpz_init(negative_n);
      mpz_neg(negative_n, n);
      if (not is_unit(a))
        {
          throw exc::engine_error("attempt to divide by a non-unit");
        }
      top = mRing->power(f->denom, negative_n);
      bottom = mRing->power(f->numer, negative_n);
      mpz_clear(negative_n);
 
      if (mRing->is_zero(bottom)) return set_non_unit_frac(f->numer);
    }
  return ring_elem(make_elem(top, bottom));
}

References local_elem::denom, ring_elem::get_local_elem(), is_unit(), make_elem(), mRing, local_elem::numer, and set_non_unit_frac().