1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
/* Return tangent of pi * X.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <math.h>
#include <math-underflow.h>
FLOAT
M_DECL_FUNC (__tanpi) (FLOAT x)
{
if (isless (M_FABS (x), M_EPSILON))
{
FLOAT ret = M_MLIT (M_PI) * x;
math_check_force_underflow (ret);
return ret;
}
if (__glibc_unlikely (isinf (x)))
__set_errno (EDOM);
FLOAT y = x - M_LIT (2.0) * M_SUF (round) (M_LIT (0.5) * x);
FLOAT absy = M_FABS (y);
if (absy == M_LIT (0.0))
/* For even integers, return +0 if positive and -0 if negative (so
matching sinpi(x)/cospi(x)). */
return M_COPYSIGN (M_LIT (0.0), x);
else if (absy == M_LIT (1.0))
/* For odd integers, return -0 if positive and +0 if negative (so
matching sinpi(x)/cospi(x)). */
return M_COPYSIGN (M_LIT (0.0), -x);
else if (absy == M_LIT (0.5))
{
/* Return infinity with positive sign for an even integer + 0.5
and negative sign for an odd integer + 0.5 (so matching
sinpi(x)/cospi(x)). */
__set_errno (ERANGE);
return 1.0 / M_COPYSIGN (M_LIT (0.0), y);
}
/* Now we only care about the value of X mod 1, not mod 2. */
else if (isgreater (absy, 0.5))
{
y -= M_COPYSIGN (M_LIT (1.0), y);
absy = M_FABS (y);
}
if (islessequal (absy, M_LIT (0.25)))
return M_SUF (__tan) (M_MLIT (M_PI) * y);
else
return M_COPYSIGN (M_LIT (1.0)
/ M_SUF (__tan) (M_MLIT (M_PI) * (M_LIT (0.5) - absy)),
y);
}
declare_mgen_alias (__tanpi, tanpi);
|
