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/* Return arc hyperbole tangent for double value.
Copyright (C) 1997-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <complex.h>
#include <math.h>
#include <math_private.h>
#include <float.h>
__complex__ double
__catanh (__complex__ double x)
{
__complex__ double res;
int rcls = fpclassify (__real__ x);
int icls = fpclassify (__imag__ x);
if (__builtin_expect (rcls <= FP_INFINITE || icls <= FP_INFINITE, 0))
{
if (icls == FP_INFINITE)
{
__real__ res = __copysign (0.0, __real__ x);
__imag__ res = __copysign (M_PI_2, __imag__ x);
}
else if (rcls == FP_INFINITE || rcls == FP_ZERO)
{
__real__ res = __copysign (0.0, __real__ x);
if (icls >= FP_ZERO)
__imag__ res = __copysign (M_PI_2, __imag__ x);
else
__imag__ res = __nan ("");
}
else
{
__real__ res = __nan ("");
__imag__ res = __nan ("");
}
}
else if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
{
res = x;
}
else
{
double i2 = __imag__ x * __imag__ x;
double num = 1.0 + __real__ x;
num = i2 + num * num;
double den = 1.0 - __real__ x;
den = i2 + den * den;
double f = num / den;
if (f < 0.5)
__real__ res = 0.25 * __ieee754_log (f);
else
{
num = 4.0 * __real__ x;
__real__ res = 0.25 * __log1p (num / den);
}
den = 1 - __real__ x * __real__ x - i2;
__imag__ res = 0.5 * __ieee754_atan2 (2.0 * __imag__ x, den);
if (fabs (__real__ res) < DBL_MIN)
{
volatile double force_underflow = __real__ res * __real__ res;
(void) force_underflow;
}
if (fabs (__imag__ res) < DBL_MIN)
{
volatile double force_underflow = __imag__ res * __imag__ res;
(void) force_underflow;
}
}
return res;
}
weak_alias (__catanh, catanh)
#ifdef NO_LONG_DOUBLE
strong_alias (__catanh, __catanhl)
weak_alias (__catanh, catanhl)
#endif
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