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
;
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
)
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
;