1/* s_atanhl.c -- long double version of s_atan.c. 2 * Conversion to long double by Ulrich Drepper, 3 * Cygnus Support, drepper@cygnus.com. 4 */ 5 6/* 7 * ==================================================== 8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 9 * 10 * Developed at SunPro, a Sun Microsystems, Inc. business. 11 * Permission to use, copy, modify, and distribute this 12 * software is freely granted, provided that this notice 13 * is preserved. 14 * ==================================================== 15 */ 16 17#if defined(LIBM_SCCS) && !defined(lint) 18static char rcsid[] = "$NetBSD: $"; 19#endif 20 21/* __ieee754_atanhl(x) 22 * Method : 23 * 1.Reduced x to positive by atanh(-x) = -atanh(x) 24 * 2.For x>=0.5 25 * 1 2x x 26 * atanhl(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------) 27 * 2 1 - x 1 - x 28 * 29 * For x<0.5 30 * atanhl(x) = 0.5*log1pl(2x+2x*x/(1-x)) 31 * 32 * Special cases: 33 * atanhl(x) is NaN if |x| > 1 with signal; 34 * atanhl(NaN) is that NaN with no signal; 35 * atanhl(+-1) is +-INF with signal. 36 * 37 */ 38 39#include "math.h" 40#include "math_private.h" 41 42#ifdef __STDC__ 43static const long double one = 1.0, huge = 1e4900L; 44#else 45static long double one = 1.0, huge = 1e4900L; 46#endif 47 48#ifdef __STDC__ 49static const long double zero = 0.0; 50#else 51static double long zero = 0.0; 52#endif 53 54#ifdef __STDC__ 55 long double __ieee754_atanhl(long double x) 56#else 57 long double __ieee754_atanhl(x) 58 long double x; 59#endif 60{ 61 long double t; 62 int32_t ix; 63 u_int32_t se,i0,i1; 64 GET_LDOUBLE_WORDS(se,i0,i1,x); 65 ix = se&0x7fff; 66 if ((ix+((((i0&0x7fffffff)|i1)|(-((i0&0x7fffffff)|i1)))>>31))>0x3fff) 67 /* |x|>1 */ 68 return (x-x)/(x-x); 69 if(ix==0x3fff) 70 return x/zero; 71 if(ix<0x3fe3&&(huge+x)>zero) return x; /* x<2**-28 */ 72 SET_LDOUBLE_EXP(x,ix); 73 if(ix<0x3ffe) { /* x < 0.5 */ 74 t = x+x; 75 t = 0.5*__log1pl(t+t*x/(one-x)); 76 } else 77 t = 0.5*__log1pl((x+x)/(one-x)); 78 if(se<=0x7fff) return t; else return -t; 79} 80