1 |
|
|
/* $OpenBSD: s_clogf.c,v 1.3 2016/09/12 19:47:02 guenther Exp $ */ |
2 |
|
|
/* |
3 |
|
|
* Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net> |
4 |
|
|
* |
5 |
|
|
* Permission to use, copy, modify, and distribute this software for any |
6 |
|
|
* purpose with or without fee is hereby granted, provided that the above |
7 |
|
|
* copyright notice and this permission notice appear in all copies. |
8 |
|
|
* |
9 |
|
|
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
10 |
|
|
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
11 |
|
|
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
12 |
|
|
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
13 |
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
14 |
|
|
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
15 |
|
|
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
16 |
|
|
*/ |
17 |
|
|
|
18 |
|
|
/* clogf.c |
19 |
|
|
* |
20 |
|
|
* Complex natural logarithm |
21 |
|
|
* |
22 |
|
|
* |
23 |
|
|
* |
24 |
|
|
* SYNOPSIS: |
25 |
|
|
* |
26 |
|
|
* void clogf(); |
27 |
|
|
* cmplxf z, w; |
28 |
|
|
* |
29 |
|
|
* clogf( &z, &w ); |
30 |
|
|
* |
31 |
|
|
* |
32 |
|
|
* |
33 |
|
|
* DESCRIPTION: |
34 |
|
|
* |
35 |
|
|
* Returns complex logarithm to the base e (2.718...) of |
36 |
|
|
* the complex argument x. |
37 |
|
|
* |
38 |
|
|
* If z = x + iy, r = sqrt( x**2 + y**2 ), |
39 |
|
|
* then |
40 |
|
|
* w = log(r) + i arctan(y/x). |
41 |
|
|
* |
42 |
|
|
* The arctangent ranges from -PI to +PI. |
43 |
|
|
* |
44 |
|
|
* |
45 |
|
|
* ACCURACY: |
46 |
|
|
* |
47 |
|
|
* Relative error: |
48 |
|
|
* arithmetic domain # trials peak rms |
49 |
|
|
* IEEE -10,+10 30000 1.9e-6 6.2e-8 |
50 |
|
|
* |
51 |
|
|
* Larger relative error can be observed for z near 1 +i0. |
52 |
|
|
* In IEEE arithmetic the peak absolute error is 3.1e-7. |
53 |
|
|
* |
54 |
|
|
*/ |
55 |
|
|
|
56 |
|
|
#include <complex.h> |
57 |
|
|
#include <math.h> |
58 |
|
|
|
59 |
|
|
float complex |
60 |
|
|
clogf(float complex z) |
61 |
|
|
{ |
62 |
|
|
float complex w; |
63 |
|
|
float p, rr, x, y; |
64 |
|
|
|
65 |
|
|
x = crealf(z); |
66 |
|
|
y = cimagf(z); |
67 |
|
|
rr = atan2f(y, x); |
68 |
|
|
p = cabsf(z); |
69 |
|
|
p = logf(p); |
70 |
|
|
w = p + rr * I; |
71 |
|
|
return (w); |
72 |
|
|
} |
73 |
|
|
DEF_STD(clogf); |