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| -rw-r--r-- | ChangeLog | 2 | ||||
| -rw-r--r-- | sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c | 67 |
2 files changed, 69 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index 7b87e2c0e6..4f8767e07b 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,7 @@ 2012-01-11 Ulrich Drepper <drepper@gmail.com> + * sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c: New file. + * sysdeps/ieee754/dbl-64/s_scalbln.c: Add branch prediction. * sysdeps/ieee754/flt-32/s_scalblnf.c: Likewise. * sysdeps/ieee754/ldbl-96/s_scalblnl.c: Likewise. diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c b/sysdeps/ieee754/dbl-64/wordsize-64/e_acosh.c new file mode 100644 index 0000000000..83c28479d3 --- /dev/null +++ b/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 (__builtin_expect (hx >= INT64_C (0x41b0000000000000), 0)) + { + /* 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 (__builtin_expect (hx > INT64_C (0x3ff0000000000000), 1)) + { + /* 1<x<2 */ + double t = x - one; + return __log1p (t + __ieee754_sqrt (2.0 * t + t * t)); + } + else if (__builtin_expect (hx == INT64_C (0x3ff0000000000000), 1)) + return 0.0; /* acosh(1) = 0 */ + else /* x < 1 */ + return (x - x) / (x - x); +} +strong_alias (__ieee754_acosh, __acosh_finite) |