6 #elif FLT_EVAL_METHOD==1
11 /* acosh(x) = log(x + sqrt(x*x-1)) */
14 union {float f
; uint32_t i
;} u
= {x
};
15 uint32_t a
= u
.i
& 0x7fffffff;
17 if (a
< 0x3f800000+(1<<23))
18 /* |x| < 2, invalid if x < 1 or nan */
19 /* up to 2ulp error in [1,1.125] */
20 return log1pf(x
-1 + sqrtf((x
-1)*(x
-1)+2*(x
-1)));
21 if (a
< 0x3f800000+(12<<23))
23 return logf(2*x
- 1/(x
+sqrtf(x
*x
-1)));
25 return logf(x
) + 0.693147180559945309417232121458176568f
;