malachite_q/arithmetic/
is_power_of_2.rs

1// Copyright © 2025 Mikhail Hogrefe
2//
3// This file is part of Malachite.
4//
5// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
6// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
7// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
8
9use crate::Rational;
10use malachite_base::num::arithmetic::traits::IsPowerOf2;
11
12impl IsPowerOf2 for Rational {
13    /// Determines whether a [`Rational`] is an integer power of 2.
14    ///
15    /// $f(x) = (\exists n \in \Z : 2^n = x)$.
16    ///
17    /// # Worst-case complexity
18    /// $T(n) = O(n)$
19    ///
20    /// $M(n) = O(1)$
21    ///
22    /// where $T$ is time, $M$ is additional memory, and $n$ is `self.significant_bits()`.
23    ///
24    /// # Examples
25    /// ```
26    /// use malachite_base::num::arithmetic::traits::IsPowerOf2;
27    /// use malachite_q::Rational;
28    ///
29    /// assert_eq!(Rational::from(0x80).is_power_of_2(), true);
30    /// assert_eq!(Rational::from_signeds(1, 8).is_power_of_2(), true);
31    /// assert_eq!(Rational::from_signeds(-1, 8).is_power_of_2(), false);
32    /// assert_eq!(Rational::from_signeds(22, 7).is_power_of_2(), false);
33    /// ```
34    fn is_power_of_2(&self) -> bool {
35        self.sign
36            && (self.denominator == 1u32 && self.numerator.is_power_of_2()
37                || self.numerator == 1u32 && self.denominator.is_power_of_2())
38    }
39}
malachite_q/arithmetic/is_power_of_2.rs

malachite_q/arithmetic/
is_power_of_2.rs
