libm/math/
scalbn.rs

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1#[cfg(f16_enabled)]
2#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
3pub fn scalbnf16(x: f16, n: i32) -> f16 {
4    super::generic::scalbn(x, n)
5}
6
7#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
8pub fn scalbnf(x: f32, n: i32) -> f32 {
9    super::generic::scalbn(x, n)
10}
11
12#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
13pub fn scalbn(x: f64, n: i32) -> f64 {
14    super::generic::scalbn(x, n)
15}
16
17#[cfg(f128_enabled)]
18#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
19pub fn scalbnf128(x: f128, n: i32) -> f128 {
20    super::generic::scalbn(x, n)
21}
22
23#[cfg(test)]
24mod tests {
25    use super::*;
26    use crate::support::{CastFrom, CastInto, Float};
27
28    // Tests against N3220
29    fn spec_test<F: Float>(f: impl Fn(F, i32) -> F)
30    where
31        u32: CastInto<F::Int>,
32        F::Int: CastFrom<i32>,
33        F::Int: CastFrom<u32>,
34    {
35        // `scalbn(±0, n)` returns `±0`.
36        assert_biteq!(f(F::NEG_ZERO, 10), F::NEG_ZERO);
37        assert_biteq!(f(F::NEG_ZERO, 0), F::NEG_ZERO);
38        assert_biteq!(f(F::NEG_ZERO, -10), F::NEG_ZERO);
39        assert_biteq!(f(F::ZERO, 10), F::ZERO);
40        assert_biteq!(f(F::ZERO, 0), F::ZERO);
41        assert_biteq!(f(F::ZERO, -10), F::ZERO);
42
43        // `scalbn(x, 0)` returns `x`.
44        assert_biteq!(f(F::MIN, 0), F::MIN);
45        assert_biteq!(f(F::MAX, 0), F::MAX);
46        assert_biteq!(f(F::INFINITY, 0), F::INFINITY);
47        assert_biteq!(f(F::NEG_INFINITY, 0), F::NEG_INFINITY);
48        assert_biteq!(f(F::ZERO, 0), F::ZERO);
49        assert_biteq!(f(F::NEG_ZERO, 0), F::NEG_ZERO);
50
51        // `scalbn(±∞, n)` returns `±∞`.
52        assert_biteq!(f(F::INFINITY, 10), F::INFINITY);
53        assert_biteq!(f(F::INFINITY, -10), F::INFINITY);
54        assert_biteq!(f(F::NEG_INFINITY, 10), F::NEG_INFINITY);
55        assert_biteq!(f(F::NEG_INFINITY, -10), F::NEG_INFINITY);
56
57        // NaN should remain NaNs.
58        assert!(f(F::NAN, 10).is_nan());
59        assert!(f(F::NAN, 0).is_nan());
60        assert!(f(F::NAN, -10).is_nan());
61        assert!(f(-F::NAN, 10).is_nan());
62        assert!(f(-F::NAN, 0).is_nan());
63        assert!(f(-F::NAN, -10).is_nan());
64    }
65
66    #[test]
67    #[cfg(f16_enabled)]
68    fn spec_test_f16() {
69        spec_test::<f16>(scalbnf16);
70    }
71
72    #[test]
73    fn spec_test_f32() {
74        spec_test::<f32>(scalbnf);
75    }
76
77    #[test]
78    fn spec_test_f64() {
79        spec_test::<f64>(scalbn);
80    }
81
82    #[test]
83    #[cfg(f128_enabled)]
84    fn spec_test_f128() {
85        spec_test::<f128>(scalbnf128);
86    }
87}
libm/math/scalbn.rs

libm/math/
scalbn.rs
