diff options
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/e_atanhl.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128/e_atanhl.c b/sysdeps/ieee754/ldbl-128/e_atanhl.c new file mode 100644 index 0000000000..dd681c847c --- /dev/null +++ b/sysdeps/ieee754/ldbl-128/e_atanhl.c @@ -0,0 +1,84 @@ +/* s_atanhl.c -- long double version of s_atan.c. + * Conversion to long double by Ulrich Drepper, + * Cygnus Support, drepper@cygnus.com. + */ + +/* + * ==================================================== + * 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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: $"; +#endif + +/* __ieee754_atanhl(x) + * Method : + * 1.Reduced x to positive by atanh(-x) = -atanh(x) + * 2.For x>=0.5 + * 1 2x x + * atanhl(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------) + * 2 1 - x 1 - x + * + * For x<0.5 + * atanhl(x) = 0.5*log1pl(2x+2x*x/(1-x)) + * + * Special cases: + * atanhl(x) is NaN if |x| > 1 with signal; + * atanhl(NaN) is that NaN with no signal; + * atanhl(+-1) is +-INF with signal. + * + */ + +#include "math.h" +#include "math_private.h" + +#ifdef __STDC__ +static const long double one = 1.0L, huge = 1e4900L; +#else +static long double one = 1.0L, huge = 1e4900L; +#endif + +#ifdef __STDC__ +static const long double zero = 0.0L; +#else +static double long zero = 0.0L; +#endif + +#ifdef __STDC__ + long double __ieee754_atanhl(long double x) +#else + long double __ieee754_atanhl(x) + long double x; +#endif +{ + long double t; + u_int32_t jx, ix; + ieee854_long_double_shape_type u; + + u.value = x; + jx = u.parts32.w0; + ix = jx & 0x7fffffff; + u.parts32.w0 = ix; + if (ix >= 0x3fff0000) /* |x| >= 1.0 or infinity or NaN */ + { + if (u.value == one) + return x/zero; + else + return (x-x)/(x-x); + } + if(ix<0x3fc60000 && (huge+x)>zero) return x; /* x < 2^-57 */ + + if(ix<0x3ffe0000) { /* x < 0.5 */ + t = u.value+u.value; + t = 0.5*__log1pl(t+t*u.value/(one-u.value)); + } else + t = 0.5*__log1pl((u.value+u.value)/(one-u.value)); + if(jx & 0x80000000) return -t; else return t; +} |