panic("d out of range")
	}

	precise := big.NewRat((1<<d)*int64(x), q) // (2ᵈ / q) * x == (2ᵈ * x) / q

	// FloatString rounds halves away from 0, and our result should always be positive,
	// so it should work as we expect. (There's no direct way to round a Rat.)
	rounded, err := strconv.ParseInt(precise.FloatString(0), 10, 64)
	if err != nil {
		panic(err)
	}

	{".55", -1, "1"},
}

func TestFloatString(t *testing.T) {
	for i, test := range floatStringTests {
		x, _ := new(Rat).SetString(test.in)

		if x.FloatString(test.prec) != test.out {
			t.Errorf("#%d got %s want %s", i, x.FloatString(test.prec), test.out)
		}
	}
}

// Test inputs to Rat.SetString. The prefix "long:" causes the test
// to be skipped except in -long mode.  (The threshold is about 500us.)

	if x.IsInt() {
		return x.a.String()
	}
	return x.String()
}

// FloatString returns a string representation of x in decimal form with prec
// digits of precision after the radix point. The last digit is rounded to
// nearest, with halves rounded away from zero.
func (x *Rat) FloatString(prec int) string {
	var buf []byte

	if x.IsInt() {
		buf = x.a.Append(buf, 10)
		if prec > 0 {

		{"(*Rat).Add", Method, 0},
		{"(*Rat).Cmp", Method, 0},
		{"(*Rat).Denom", Method, 0},
		{"(*Rat).Float32", Method, 4},
		{"(*Rat).Float64", Method, 1},
		{"(*Rat).FloatPrec", Method, 22},
		{"(*Rat).FloatString", Method, 0},
		{"(*Rat).GobDecode", Method, 0},
		{"(*Rat).GobEncode", Method, 0},
		{"(*Rat).Inv", Method, 0},
		{"(*Rat).IsInt", Method, 0},
		{"(*Rat).MarshalText", Method, 3},