1 /* Compute cosine of argument.
2 Copyright (C) 2018 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
21 #include <math-barriers.h>
22 #include <libm-alias-float.h>
23 #include "math_config.h"
24 #include "s_sincosf.h"
27 # define COSF_FUNC __cosf
29 # define COSF_FUNC COSF
32 /* Fast cosf implementation. Worst-case ULP is 0.5607, maximum relative
33 error is 0.5303 * 2^-23. A single-step range reduction is used for
34 small values. Large inputs have their range reduced using fast integer
43 const sincos_t
*p
= &__sincosf_table
[0];
45 if (abstop12 (y
) < abstop12 (pio4
))
49 if (__glibc_unlikely (abstop12 (y
) < abstop12 (0x1p
-12f
)))
52 return sinf_poly (x
, x2
, p
, 1);
54 else if (__glibc_likely (abstop12 (y
) < abstop12 (120.0f
)))
56 x
= reduce_fast (x
, p
, &n
);
58 /* Setup the signs for sin and cos. */
62 p
= &__sincosf_table
[1];
64 return sinf_poly (x
* s
, x
* x
, p
, n
^ 1);
66 else if (abstop12 (y
) < abstop12 (INFINITY
))
68 uint32_t xi
= asuint (y
);
71 x
= reduce_large (xi
, &n
);
73 /* Setup signs for sin and cos - include original sign. */
74 s
= p
->sign
[(n
+ sign
) & 3];
77 p
= &__sincosf_table
[1];
79 return sinf_poly (x
* s
, x
* x
, p
, n
^ 1);
82 return __math_invalidf (y
);
86 libm_alias_float (__cos
, cos
)