glibc/math/s_catanl.c

153 lines
4.1 KiB
C

/* Return arc tangent of complex long 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>
/* 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
__complex__ long double
__catanl (__complex__ long double x)
{
__complex__ long double res;
int rcls = fpclassify (__real__ x);
int icls = fpclassify (__imag__ x);
if (__builtin_expect (rcls <= FP_INFINITE || icls <= FP_INFINITE, 0))
{
if (rcls == FP_INFINITE)
{
__real__ res = __copysignl (M_PI_2l, __real__ x);
__imag__ res = __copysignl (0.0, __imag__ x);
}
else if (icls == FP_INFINITE)
{
if (rcls >= FP_ZERO)
__real__ res = __copysignl (M_PI_2l, __real__ x);
else
__real__ res = __nanl ("");
__imag__ res = __copysignl (0.0, __imag__ x);
}
else if (icls == FP_ZERO || icls == FP_INFINITE)
{
__real__ res = __nanl ("");
__imag__ res = __copysignl (0.0, __imag__ x);
}
else
{
__real__ res = __nanl ("");
__imag__ res = __nanl ("");
}
}
else if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
{
res = x;
}
else
{
if (fabsl (__real__ x) >= 16.0L / LDBL_EPSILON
|| fabsl (__imag__ x) >= 16.0L / LDBL_EPSILON)
{
__real__ res = __copysignl (M_PI_2l, __real__ x);
if (fabsl (__real__ x) <= 1.0L)
__imag__ res = 1.0L / __imag__ x;
else if (fabsl (__imag__ x) <= 1.0L)
__imag__ res = __imag__ x / __real__ x / __real__ x;
else
{
long double h = __ieee754_hypotl (__real__ x / 2.0L,
__imag__ x / 2.0L);
__imag__ res = __imag__ x / h / h / 4.0L;
}
}
else
{
long double den, absx, absy;
absx = fabsl (__real__ x);
absy = fabsl (__imag__ x);
if (absx < absy)
{
long double t = absx;
absx = absy;
absy = t;
}
if (absy < LDBL_EPSILON / 2.0L)
den = (1.0L - absx) * (1.0L + absx);
else if (absx >= 1.0L)
den = (1.0L - absx) * (1.0L + absx) - absy * absy;
else if (absx >= 0.75L || absy >= 0.5L)
den = -__x2y2m1l (absx, absy);
else
den = (1.0L - absx) * (1.0L + absx) - absy * absy;
__real__ res = 0.5L * __ieee754_atan2l (2.0L * __real__ x, den);
if (fabsl (__imag__ x) == 1.0L
&& fabsl (__real__ x) < LDBL_EPSILON * LDBL_EPSILON)
__imag__ res = (__copysignl (0.5L, __imag__ x)
* (M_LN2l - __ieee754_logl (fabsl (__real__ x))));
else
{
long double r2 = 0.0L, num, f;
if (fabsl (__real__ x) >= LDBL_EPSILON * LDBL_EPSILON)
r2 = __real__ x * __real__ x;
num = __imag__ x + 1.0L;
num = r2 + num * num;
den = __imag__ x - 1.0L;
den = r2 + den * den;
f = num / den;
if (f < 0.5L)
__imag__ res = 0.25L * __ieee754_logl (f);
else
{
num = 4.0L * __imag__ x;
__imag__ res = 0.25L * __log1pl (num / den);
}
}
}
if (fabsl (__real__ res) < LDBL_MIN)
{
volatile long double force_underflow = __real__ res * __real__ res;
(void) force_underflow;
}
if (fabsl (__imag__ res) < LDBL_MIN)
{
volatile long double force_underflow = __imag__ res * __imag__ res;
(void) force_underflow;
}
}
return res;
}
weak_alias (__catanl, catanl)