set_from_mpq()

bool DRing::set_from_mpq	(	TowerPolynomial &	result,
		mpq_srcptr	r )

Definition at line 1510 of file dpoly.cpp.

{
  // returns false if r doesn't lift
  mpz_t a;
  mpz_init(a);
  mpz_mod_ui(a, mpq_numref(r), P);
  long ctop = mpz_get_si(a);
  mpz_mod_ui(a, mpq_denref(r), P);
  long cbottom = mpz_get_si(a);
  mpz_clear(a);
  if (ctop < 0) ctop += P;
  if (cbottom < 0) cbottom += P;
  if (cbottom == 0)
    {
      result = nullptr;
      return false;
    }
  ZZp_INVERT(P, cbottom, cbottom);
  ZZp_MULT(P, ctop, cbottom);
 
  result = D.from_long(level, ctop);
  return true;
}

References D, level, P, result(), ZZp_INVERT(), and ZZp_MULT().