| /* from: FreeBSD: head/lib/msun/src/e_atanh.c 176451 2008-02-22 02:30:36Z das */ |
| |
| /* @(#)e_atanh.c 1.3 95/01/18 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunSoft, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| * |
| */ |
| |
| #include <sys/cdefs.h> |
| __FBSDID("$FreeBSD$"); |
| |
| /* |
| * See e_atanh.c for complete comments. |
| * |
| * Converted to long double by David Schultz <das@FreeBSD.ORG> and |
| * Bruce D. Evans. |
| */ |
| |
| #include <float.h> |
| #ifdef __i386__ |
| #include <ieeefp.h> |
| #endif |
| |
| #include "fpmath.h" |
| #include "math.h" |
| #include "math_private.h" |
| |
| /* EXP_TINY is the threshold below which we use atanh(x) ~= x. */ |
| #if LDBL_MANT_DIG == 64 |
| #define EXP_TINY -34 |
| #elif LDBL_MANT_DIG == 113 |
| #define EXP_TINY -58 |
| #else |
| #error "Unsupported long double format" |
| #endif |
| |
| #if LDBL_MAX_EXP != 0x4000 |
| /* We also require the usual expsign encoding. */ |
| #error "Unsupported long double format" |
| #endif |
| |
| #define BIAS (LDBL_MAX_EXP - 1) |
| |
| static const double one = 1.0, huge = 1e300; |
| static const double zero = 0.0; |
| |
| long double |
| atanhl(long double x) |
| { |
| long double t; |
| uint16_t hx, ix; |
| |
| ENTERI(); |
| GET_LDBL_EXPSIGN(hx, x); |
| ix = hx & 0x7fff; |
| if (ix >= 0x3fff) /* |x| >= 1, or NaN or misnormal */ |
| RETURNI(fabsl(x) == 1 ? x / zero : (x - x) / (x - x)); |
| if (ix < BIAS + EXP_TINY && (huge + x) > zero) |
| RETURNI(x); /* x is tiny */ |
| SET_LDBL_EXPSIGN(x, ix); |
| if (ix < 0x3ffe) { /* |x| < 0.5, or misnormal */ |
| t = x+x; |
| t = 0.5*log1pl(t+t*x/(one-x)); |
| } else |
| t = 0.5*log1pl((x+x)/(one-x)); |
| RETURNI((hx & 0x8000) == 0 ? t : -t); |
| } |