return bigInteger.signum();
    }

    @Override
    BigInteger toX(double d, RoundingMode mode) {
      return DoubleMath.roundToBigInteger(d, mode);
    }

    @Override
    BigInteger minus(BigInteger a, BigInteger b) {
      return a.subtract(b);
    }
  }

  /**
   * Returns the result of dividing {@code p} by {@code q}, rounding using the specified {@code
   * RoundingMode}.
   *