1 | /* origin: FreeBSD /usr/src/lib/msun/src/k_cosf.c */ |
2 | /* |
3 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
4 | * Debugged and optimized by Bruce D. Evans. |
5 | */ |
6 | /* |
7 | * ==================================================== |
8 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
9 | * |
10 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
11 | * Permission to use, copy, modify, and distribute this |
12 | * software is freely granted, provided that this notice |
13 | * is preserved. |
14 | * ==================================================== |
15 | */ |
16 | |
17 | /* |cos(x) - c(x)| < 2**-34.1 (~[-5.37e-11, 5.295e-11]). */ |
18 | const C0: f64 = -0.499999997251031003120; /* -0x1ffffffd0c5e81.0p-54 */ |
19 | const C1: f64 = 0.0416666233237390631894; /* 0x155553e1053a42.0p-57 */ |
20 | const C2: f64 = -0.00138867637746099294692; /* -0x16c087e80f1e27.0p-62 */ |
21 | const C3: f64 = 0.0000243904487962774090654; /* 0x199342e0ee5069.0p-68 */ |
22 | |
23 | #[cfg_attr (all(test, assert_no_panic), no_panic::no_panic)] |
24 | pub(crate) fn k_cosf(x: f64) -> f32 { |
25 | let z: f64 = x * x; |
26 | let w: f64 = z * z; |
27 | let r: f64 = C2 + z * C3; |
28 | (((1.0 + z * C0) + w * C1) + (w * z) * r) as f32 |
29 | } |
30 | |