Last change
on this file since 351 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:
477 bytes
|
Line | |
---|
1 | #include "libm.h"
|
---|
2 |
|
---|
3 | /* k is such that k*ln2 has minimal relative error and x - kln2 > log(FLT_MIN) */
|
---|
4 | static const int k = 235;
|
---|
5 | static const float kln2 = 0x1.45c778p+7f;
|
---|
6 |
|
---|
7 | /* expf(x)/2 for x >= log(FLT_MAX), slightly better than 0.5f*expf(x/2)*expf(x/2) */
|
---|
8 | float __expo2f(float x)
|
---|
9 | {
|
---|
10 | float scale;
|
---|
11 |
|
---|
12 | /* note that k is odd and scale*scale overflows */
|
---|
13 | SET_FLOAT_WORD(scale, (uint32_t)(0x7f + k/2) << 23);
|
---|
14 | /* exp(x - k ln2) * 2**(k-1) */
|
---|
15 | return expf(x - kln2) * scale * scale;
|
---|
16 | }
|
---|
Note:
See
TracBrowser
for help on using the repository browser.