| 0,0 → 1,26 |
|---|
| #include <math.h> |
| #include <errno.h> |
| #include "fastmath.h" |
| |
| /* acosh(x) = log (x + sqrt(x * x - 1)) */ |
| double acosh (double x) |
| { |
| if (isnan (x)) |
| return x; |
| |
| if (x < 1.0) |
| { |
| errno = EDOM; |
| return nan(""); |
| } |
| |
| if (x > 0x1p32) |
| /* Avoid overflow (and unnecessary calculation when |
| sqrt (x * x - 1) == x). GCC optimizes by replacing |
| the long double M_LN2 const with a fldln2 insn. */ |
| return __fast_log (x) + 6.9314718055994530941723E-1L; |
| |
| /* Since x >= 1, the arg to log will always be greater than |
| the fyl2xp1 limit (approx 0.29) so just use logl. */ |
| return __fast_log (x + __fast_sqrt((x + 1.0) * (x - 1.0))); |
| } |