blob: 53551e56e60c0a1c6754517210ce7cea4b17c169 (
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
65
66
67
68
69
70
71
72
73
74
|
/* @(#)z_atan.c 1.0 98/08/13 */
/*
FUNCTION
<<atan>>, <<atanf>>---arc tangent
INDEX
atan
INDEX
atanf
SYNOPSIS
#include <math.h>
double atan(double <[x]>);
float atanf(float <[x]>);
DESCRIPTION
<<atan>> computes the inverse tangent (arc tangent) of the input value.
<<atanf>> is identical to <<atan>>, save that it operates on <<floats>>.
RETURNS
@ifnottex
<<atan>> returns a value in radians, in the range of -pi/2 to pi/2.
@end ifnottex
@tex
<<atan>> returns a value in radians, in the range of $-\pi/2$ to $\pi/2$.
@end tex
PORTABILITY
<<atan>> is ANSI C. <<atanf>> is an extension.
*/
/******************************************************************
* Arctangent
*
* Input:
* x - floating point value
*
* Output:
* arctan of x
*
* Description:
* This routine returns the arctan of x.
*
*****************************************************************/
#include "fdlibm.h"
#include "zmath.h"
#ifndef _DOUBLE_IS_32BITS
double
atan (double x)
{
switch (numtest (x))
{
case NAN:
errno = EDOM;
return (x);
case INF:
/* this should check to see if neg NaN or pos NaN... */
return (__PI_OVER_TWO);
case 0:
return (0.0);
default:
return (atangent (x, 0, 0, 0));
}
}
#endif /* _DOUBLE_IS_32BITS */
|
