blob: e75ee3d87e0ffa89b7b5c415f5e71f7d12ae07de (
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
|
/* Copyright (C) 1991 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <errno.h>
#include <math.h>
/* Return the inverse sine of X. */
double
DEFUN(asin, (x), double x)
{
double abs_x;
if (__isnan(x))
{
errno = EDOM;
return x;
}
abs_x = fabs(x);
if (abs_x <= 0.5)
return atan2(x, sqrt(1.0 - (x * x)));
else
{
double t = 1.0 - abs_x;
return atan2(x, sqrt((t + t) - (t * t)));
}
}
|
