malachite_q/arithmetic/
neg.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 core::ops::Neg;
11use malachite_base::num::arithmetic::traits::NegAssign;
12use malachite_base::num::basic::traits::Zero;
13use malachite_base::num::logic::traits::NotAssign;
14
15impl Neg for Rational {
16    type Output = Self;
17
18    /// Negates a [`Rational`], taking it by value.
19    ///
20    /// $$
21    /// f(x) = -x.
22    /// $$
23    ///
24    /// # Worst-case complexity
25    /// Constant time and additional memory.
26    ///
27    /// # Examples
28    /// ```
29    /// use malachite_base::num::basic::traits::Zero;
30    /// use malachite_q::Rational;
31    ///
32    /// assert_eq!(-Rational::ZERO, 0);
33    /// assert_eq!((-Rational::from_signeds(22, 7)).to_string(), "-22/7");
34    /// assert_eq!((-Rational::from_signeds(-22, 7)).to_string(), "22/7");
35    /// ```
36    fn neg(mut self) -> Self {
37        if self.numerator != 0 {
38            self.sign.not_assign();
39        }
40        self
41    }
42}
43
44impl Neg for &Rational {
45    type Output = Rational;
46
47    /// Negates a [`Rational`], taking it by reference.
48    ///
49    /// $$
50    /// f(x) = -x.
51    /// $$
52    ///
53    /// # Worst-case complexity
54    /// $T(n) = O(n)$
55    ///
56    /// $M(n) = O(n)$
57    ///
58    /// where $T$ is time, $M$ is additional memory, and $n$ is `self.significant_bits()`.
59    ///
60    /// # Examples
61    /// ```
62    /// use malachite_base::num::basic::traits::Zero;
63    /// use malachite_q::Rational;
64    ///
65    /// assert_eq!(-&Rational::ZERO, 0);
66    /// assert_eq!((-&Rational::from_signeds(22, 7)).to_string(), "-22/7");
67    /// assert_eq!((-&Rational::from_signeds(-22, 7)).to_string(), "22/7");
68    /// ```
69    fn neg(self) -> Rational {
70        if self.numerator == 0 {
71            Rational::ZERO
72        } else {
73            Rational {
74                sign: !self.sign,
75                numerator: self.numerator.clone(),
76                denominator: self.denominator.clone(),
77            }
78        }
79    }
80}
81
82impl NegAssign for Rational {
83    /// Negates a [`Rational`] in place.
84    ///
85    /// $$
86    /// x \gets -x.
87    /// $$
88    ///
89    /// # Worst-case complexity
90    /// Constant time and additional memory.
91    ///
92    /// # Examples
93    /// ```
94    /// use malachite_base::num::arithmetic::traits::NegAssign;
95    /// use malachite_base::num::basic::traits::Zero;
96    /// use malachite_q::Rational;
97    ///
98    /// let mut x = Rational::ZERO;
99    /// x.neg_assign();
100    /// assert_eq!(x, 0);
101    ///
102    /// let mut x = Rational::from_signeds(22, 7);
103    /// x.neg_assign();
104    /// assert_eq!(x.to_string(), "-22/7");
105    ///
106    /// let mut x = Rational::from_signeds(-22, 7);
107    /// x.neg_assign();
108    /// assert_eq!(x.to_string(), "22/7");
109    /// ```
110    fn neg_assign(&mut self) {
111        if self.numerator != 0 {
112            self.sign.not_assign();
113        }
114    }
115}
malachite_q/arithmetic/neg.rs

malachite_q/arithmetic/
neg.rs
