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77a2a8b4 | 1 | /* k_cosf.c -- float version of k_cos.c |
688903eb | 2 | Copyright (C) 2011-2018 Free Software Foundation, Inc. |
77a2a8b4 AZ |
3 | This file is part of the GNU C Library. |
4 | Contributed by Adhemerval Zanella <azanella@br.ibm.com>, 2011 | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Library General Public License as | |
8 | published by the Free Software Foundation; either version 2 of the | |
9 | License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Library General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Library General Public | |
59ba27a6 PE |
17 | License along with the GNU C Library; see the file COPYING.LIB. If |
18 | not, see <http://www.gnu.org/licenses/>. */ | |
77a2a8b4 | 19 | |
1ed0291c | 20 | #include <math.h> |
73a68f94 | 21 | #include <fenv.h> |
1ed0291c | 22 | #include <math_private.h> |
77a2a8b4 AZ |
23 | |
24 | static const float twom27 = 7.4505806e-09; | |
25 | static const float dot3 = 3.0000001e-01; | |
26 | static const float dot78125 = 7.8125000e-01; | |
27 | ||
28 | static const float one = 1.0000000000e+00; | |
29 | static const float C1 = 4.1666667908e-02; | |
30 | static const float C2 = -1.3888889225e-03; | |
31 | static const float C3 = 2.4801587642e-05; | |
32 | static const float C4 = -2.7557314297e-07; | |
33 | static const float C5 = 2.0875723372e-09; | |
34 | static const float C6 = -1.1359647598e-11; | |
35 | ||
36 | float | |
37 | __kernel_cosf (float x, float y) | |
38 | { | |
39 | float a, hz, z, r, qx; | |
40 | float ix; | |
41 | ix = __builtin_fabsf (x); | |
42 | if (ix < twom27) | |
43 | { /* |x| < 2**-27 */ | |
73a68f94 AZ |
44 | __feraiseexcept (FE_INEXACT); |
45 | return one; | |
77a2a8b4 AZ |
46 | } |
47 | z = x * x; | |
48 | r = z * (C1 + z * (C2 + z * (C3 + z * (C4 + z * (C5 + z * C6))))); | |
49 | if (ix < dot3) /* if |x| < 0.3 */ | |
50 | return one - ((float) 0.5 * z - (z * r - x * y)); | |
51 | else | |
52 | { | |
53 | if (ix > dot78125) | |
54 | { /* x > 0.78125 */ | |
55 | qx = (float) 0.28125; | |
56 | } | |
57 | else | |
58 | { | |
59 | qx = ix / 4.0; | |
60 | } | |
61 | hz = (float) 0.5 *z - qx; | |
62 | a = one - qx; | |
63 | return a - (hz - (z * r - x * y)); | |
64 | } | |
65 | } |