diff options
Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c')
| -rw-r--r-- | REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c b/REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c new file mode 100644 index 0000000000..ccccdaf106 --- /dev/null +++ b/REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c @@ -0,0 +1,67 @@ +/* Optimized for 64-bit by Ulrich Drepper <drepper@gmail.com>, 2012 */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +/* __ieee754_acosh(x) + * Method : + * Based on + * acosh(x) = log [ x + sqrt(x*x-1) ] + * we have + * acosh(x) := log(x)+ln2, if x is large; else + * acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else + * acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1. + * + * Special cases: + * acosh(x) is NaN with signal if x<1. + * acosh(NaN) is NaN without signal. + */ + +#include <math.h> +#include <math_private.h> + +static const double +one = 1.0, +ln2 = 6.93147180559945286227e-01; /* 0x3FE62E42, 0xFEFA39EF */ + +double +__ieee754_acosh (double x) +{ + int64_t hx; + EXTRACT_WORDS64 (hx, x); + + if (hx > INT64_C (0x4000000000000000)) + { + if (__glibc_unlikely (hx >= INT64_C (0x41b0000000000000))) + { + /* x > 2**28 */ + if (hx >= INT64_C (0x7ff0000000000000)) + /* x is inf of NaN */ + return x + x; + else + return __ieee754_log (x) + ln2;/* acosh(huge)=log(2x) */ + } + + /* 2**28 > x > 2 */ + double t = x * x; + return __ieee754_log (2.0 * x - one / (x + __ieee754_sqrt (t - one))); + } + else if (__glibc_likely (hx > INT64_C (0x3ff0000000000000))) + { + /* 1<x<2 */ + double t = x - one; + return __log1p (t + __ieee754_sqrt (2.0 * t + t * t)); + } + else if (__glibc_likely (hx == INT64_C (0x3ff0000000000000))) + return 0.0; /* acosh(1) = 0 */ + else /* x < 1 */ + return (x - x) / (x - x); +} +strong_alias (__ieee754_acosh, __acosh_finite) |