blob: 394721a9fdd6750c717f606c10f8cee8985ce2ff (
plain)
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
|
/* Auxiliary routine for the Bessel functions (j0f, y0f, j1f, y1f).
Copyright (C) 2021 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/>. */
#ifndef _MATH_REDUCE_AUX_H
#define _MATH_REDUCE_AUX_H
#include <math.h>
#include <math_private.h>
#include <s_sincosf.h>
/* Return h and update n such that:
Now x - pi/4 - alpha = h + n*pi/2 mod (2*pi). */
static inline double
reduce_aux (float x, int *n, double alpha)
{
double h;
h = reduce_large (asuint (x), n);
/* Now |x| = h+n*pi/2 mod 2*pi. */
/* Recover sign. */
if (x < 0)
{
h = -h;
*n = -*n;
}
/* Subtract pi/4. */
double piover2 = 0xc.90fdaa22168cp-3;
if (h >= 0)
h -= piover2 / 2;
else
{
h += piover2 / 2;
(*n) --;
}
/* Subtract alpha and reduce if needed mod pi/2. */
h -= alpha;
if (h > piover2)
{
h -= piover2;
(*n) ++;
}
else if (h < -piover2)
{
h += piover2;
(*n) --;
}
return h;
}
#endif
|
