Last change
on this file since 403 was 337, checked in by coas-nagasima, 6 years ago |
ASP3版ECNLを追加
|
-
Property svn:eol-style
set to
native
-
Property svn:mime-type
set to
text/x-csrc;charset=UTF-8
|
File size:
578 bytes
|
Line | |
---|
1 | #include "libm.h"
|
---|
2 |
|
---|
3 | /* atanh(x) = log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2 ~= x + x^3/3 + o(x^5) */
|
---|
4 | float atanhf(float x)
|
---|
5 | {
|
---|
6 | union {float f; uint32_t i;} u = {.f = x};
|
---|
7 | unsigned s = u.i >> 31;
|
---|
8 | float_t y;
|
---|
9 |
|
---|
10 | /* |x| */
|
---|
11 | u.i &= 0x7fffffff;
|
---|
12 | y = u.f;
|
---|
13 |
|
---|
14 | if (u.i < 0x3f800000 - (1<<23)) {
|
---|
15 | if (u.i < 0x3f800000 - (32<<23)) {
|
---|
16 | /* handle underflow */
|
---|
17 | if (u.i < (1<<23))
|
---|
18 | FORCE_EVAL((float)(y*y));
|
---|
19 | } else {
|
---|
20 | /* |x| < 0.5, up to 1.7ulp error */
|
---|
21 | y = 0.5f*log1pf(2*y + 2*y*y/(1-y));
|
---|
22 | }
|
---|
23 | } else {
|
---|
24 | /* avoid overflow */
|
---|
25 | y = 0.5f*log1pf(2*(y/(1-y)));
|
---|
26 | }
|
---|
27 | return s ? -y : y;
|
---|
28 | }
|
---|
Note:
See
TracBrowser
for help on using the repository browser.