1 /* s_atanhl.c -- __float128 version of s_atan.c.
2 * Conversion to __float128 by Ulrich Drepper,
3 * Cygnus Support, drepper@cygnus.com.
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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
14 * ====================================================
19 * 1.Reduced x to positive by atanh(-x) = -atanh(x)
22 * atanhl(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
26 * atanhl(x) = 0.5*log1pl(2x+2x*x/(1-x))
29 * atanhl(x) is NaN if |x| > 1 with signal;
30 * atanhl(NaN) is that NaN with no signal;
31 * atanhl(+-1) is +-INF with signal.
35 #include "quadmath-imp.h"
37 static const __float128 one = 1.0Q, huge = 1e4900Q;
38 static const __float128 zero = 0.0Q;
51 if (ix >= 0x3fff0000) /* |x| >= 1.0 or infinity or NaN */
58 if(ix<0x3fc60000 && (huge+x)>zero) return x; /* x < 2^-57 */
60 if(ix<0x3ffe0000) { /* x < 0.5 */
62 t = 0.5*log1pq(t+t*u.value/(one-u.value));
64 t = 0.5*log1pq((u.value+u.value)/(one-u.value));
65 if(jx & 0x80000000) return -t; else return t;