/rust/registry/src/index.crates.io-1949cf8c6b5b557f/libm-0.2.16/src/math/exp10.rs
Line | Count | Source |
1 | | use super::{exp2, modf, pow}; |
2 | | |
3 | | const LN10: f64 = 3.32192809488736234787031942948939; |
4 | | const P10: &[f64] = &[ |
5 | | 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10, 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1, |
6 | | 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15, |
7 | | ]; |
8 | | |
9 | | /// Calculates 10 raised to the power of `x` (f64). |
10 | | #[cfg_attr(assert_no_panic, no_panic::no_panic)] |
11 | 0 | pub fn exp10(x: f64) -> f64 { |
12 | | select_implementation! { |
13 | | name: x87_exp10, |
14 | | use_arch_required: x86_no_sse, |
15 | | args: x, |
16 | | } |
17 | | |
18 | 0 | let (mut y, n) = modf(x); |
19 | 0 | let u: u64 = n.to_bits(); |
20 | | /* fabs(n) < 16 without raising invalid on nan */ |
21 | 0 | if ((u >> 52) & 0x7ff) < 0x3ff + 4 { |
22 | 0 | if y == 0.0 { |
23 | 0 | return i!(P10, ((n as isize) + 15) as usize); |
24 | 0 | } |
25 | 0 | y = exp2(LN10 * y); |
26 | 0 | return y * i!(P10, ((n as isize) + 15) as usize); |
27 | 0 | } |
28 | 0 | return pow(10.0, x); |
29 | 0 | } |