source: azure_iot_hub/trunk/musl-1.1.18/src/math/__expo2f.c@ 389

Last change on this file since 389 was 389, checked in by coas-nagasima, 5 years ago

ビルドが通るよう更新
  • 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) */
4static const int k = 235;
5static 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) */
8float __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.