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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libquadmath/math/atanhq.c | |
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Diffstat (limited to 'libquadmath/math/atanhq.c')
-rw-r--r-- | libquadmath/math/atanhq.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/libquadmath/math/atanhq.c b/libquadmath/math/atanhq.c new file mode 100644 index 000000000..73db957d3 --- /dev/null +++ b/libquadmath/math/atanhq.c @@ -0,0 +1,66 @@ +/* s_atanhl.c -- __float128 version of s_atan.c. + * Conversion to __float128 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. + * ==================================================== + */ + +/* __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 "quadmath-imp.h" + +static const __float128 one = 1.0Q, huge = 1e4900Q; +static const __float128 zero = 0.0Q; + +__float128 +atanhq (__float128 x) +{ + __float128 t; + uint32_t jx, ix; + ieee854_float128 u; + + u.value = x; + jx = u.words32.w0; + ix = jx & 0x7fffffff; + u.words32.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*log1pq(t+t*u.value/(one-u.value)); + } else + t = 0.5*log1pq((u.value+u.value)/(one-u.value)); + if(jx & 0x80000000) return -t; else return t; +} |