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/* Return arc hyperbole sine for long double value, with the imaginary
part of the result possibly adjusted for use in computing other
functions.
Copyright (C) 1997-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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>
/* To avoid spurious overflows, use this definition to treat IBM long
double as approximating an IEEE-style format. */
#if LDBL_MANT_DIG == 106
# undef LDBL_EPSILON
# define LDBL_EPSILON 0x1p-106L
#endif
/* Return the complex inverse hyperbolic sine of finite nonzero Z,
with the imaginary part of the result subtracted from pi/2 if ADJ
is nonzero. */
__complex__ long double
__kernel_casinhl (__complex__ long double x, int adj)
{
__complex__ long double res;
long double rx, ix;
__complex__ long double y;
/* Avoid cancellation by reducing to the first quadrant. */
rx = fabsl (__real__ x);
ix = fabsl (__imag__ x);
if (rx >= 1.0L / LDBL_EPSILON || ix >= 1.0L / LDBL_EPSILON)
{
/* For large x in the first quadrant, x + csqrt (1 + x * x)
is sufficiently close to 2 * x to make no significant
difference to the result; avoid possible overflow from
the squaring and addition. */
__real__ y = rx;
__imag__ y = ix;
if (adj)
{
long double t = __real__ y;
__real__ y = __copysignl (__imag__ y, __imag__ x);
__imag__ y = t;
}
res = __clogl (y);
__real__ res += M_LN2l;
}
else if (rx >= 0.5L && ix < LDBL_EPSILON / 8.0L)
{
long double s = __ieee754_hypotl (1.0L, rx);
__real__ res = __ieee754_logl (rx + s);
if (adj)
__imag__ res = __ieee754_atan2l (s, __imag__ x);
else
__imag__ res = __ieee754_atan2l (ix, s);
}
else if (rx < LDBL_EPSILON / 8.0L && ix >= 1.5L)
{
long double s = __ieee754_sqrtl ((ix + 1.0L) * (ix - 1.0L));
__real__ res = __ieee754_logl (ix + s);
if (adj)
__imag__ res = __ieee754_atan2l (rx, __copysignl (s, __imag__ x));
else
__imag__ res = __ieee754_atan2l (s, rx);
}
else if (ix > 1.0L && ix < 1.5L && rx < 0.5L)
{
if (rx < LDBL_EPSILON * LDBL_EPSILON)
{
long double ix2m1 = (ix + 1.0L) * (ix - 1.0L);
long double s = __ieee754_sqrtl (ix2m1);
__real__ res = __log1pl (2.0L * (ix2m1 + ix * s)) / 2.0L;
if (adj)
__imag__ res = __ieee754_atan2l (rx, __copysignl (s, __imag__ x));
else
__imag__ res = __ieee754_atan2l (s, rx);
}
else
{
long double ix2m1 = (ix + 1.0L) * (ix - 1.0L);
long double rx2 = rx * rx;
long double f = rx2 * (2.0L + rx2 + 2.0L * ix * ix);
long double d = __ieee754_sqrtl (ix2m1 * ix2m1 + f);
long double dp = d + ix2m1;
long double dm = f / dp;
long double r1 = __ieee754_sqrtl ((dm + rx2) / 2.0L);
long double r2 = rx * ix / r1;
__real__ res
= __log1pl (rx2 + dp + 2.0L * (rx * r1 + ix * r2)) / 2.0L;
if (adj)
__imag__ res = __ieee754_atan2l (rx + r1, __copysignl (ix + r2,
__imag__ x));
else
__imag__ res = __ieee754_atan2l (ix + r2, rx + r1);
}
}
else if (ix == 1.0L && rx < 0.5L)
{
if (rx < LDBL_EPSILON / 8.0L)
{
__real__ res = __log1pl (2.0L * (rx + __ieee754_sqrtl (rx))) / 2.0L;
if (adj)
__imag__ res = __ieee754_atan2l (__ieee754_sqrtl (rx),
__copysignl (1.0L, __imag__ x));
else
__imag__ res = __ieee754_atan2l (1.0L, __ieee754_sqrtl (rx));
}
else
{
long double d = rx * __ieee754_sqrtl (4.0L + rx * rx);
long double s1 = __ieee754_sqrtl ((d + rx * rx) / 2.0L);
long double s2 = __ieee754_sqrtl ((d - rx * rx) / 2.0L);
__real__ res = __log1pl (rx * rx + d + 2.0L * (rx * s1 + s2)) / 2.0L;
if (adj)
__imag__ res = __ieee754_atan2l (rx + s1,
__copysignl (1.0L + s2,
__imag__ x));
else
__imag__ res = __ieee754_atan2l (1.0L + s2, rx + s1);
}
}
else
{
__real__ y = (rx - ix) * (rx + ix) + 1.0L;
__imag__ y = 2.0L * rx * ix;
y = __csqrtl (y);
__real__ y += rx;
__imag__ y += ix;
if (adj)
{
long double t = __real__ y;
__real__ y = __copysignl (__imag__ y, __imag__ x);
__imag__ y = t;
}
res = __clogl (y);
}
/* Give results the correct sign for the original argument. */
__real__ res = __copysignl (__real__ res, __real__ x);
__imag__ res = __copysignl (__imag__ res, (adj ? 1.0L : __imag__ x));
return res;
}
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