diff options
Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c')
| -rw-r--r-- | REORG.TODO/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c b/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c new file mode 100644 index 0000000000..b576f42030 --- /dev/null +++ b/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c @@ -0,0 +1,71 @@ +/* @(#)e_atanh.c 5.1 93/09/24 */ +/* + * ==================================================== + * 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_atanh(x) + * Method : + * 1.Reduced x to positive by atanh(-x) = -atanh(x) + * 2.For x>=0.5 + * 1 2x x + * atanh(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------) + * 2 1 - x 1 - x + * + * For x<0.5 + * atanh(x) = 0.5*log1p(2x+2x*x/(1-x)) + * + * Special cases: + * atanh(x) is NaN if |x| > 1 with signal; + * atanh(NaN) is that NaN with no signal; + * atanh(+-1) is +-INF with signal. + * + */ + +#include <float.h> +#include <math.h> +#include <math_private.h> + +static const long double one = 1.0L, huge = 1e300L; + +static const long double zero = 0.0L; + +long double +__ieee754_atanhl(long double x) +{ + long double t; + int64_t hx,ix; + double xhi; + + xhi = ldbl_high (x); + EXTRACT_WORDS64 (hx, xhi); + ix = hx&0x7fffffffffffffffLL; + if (ix >= 0x3ff0000000000000LL) { /* |x|>=1 */ + if (ix > 0x3ff0000000000000LL) + return (x-x)/(x-x); + t = fabsl (x); + if (t > one) + return (x-x)/(x-x); + if (t == one) + return x/zero; + } + if(ix<0x3c70000000000000LL&&(huge+x)>zero) /* x<2**-56 */ + { + math_check_force_underflow (x); + return x; + } + x = fabsl (x); + if(ix<0x3fe0000000000000LL) { /* x < 0.5 */ + t = x+x; + t = 0.5*__log1pl(t+t*x/(one-x)); + } else + t = 0.5*__log1pl((x+x)/(one-x)); + if(hx>=0) return t; else return -t; +} +strong_alias (__ieee754_atanhl, __atanhl_finite) |