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/* Compute complex base 10 logarithm.
Copyright (C) 1997-2015 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 underflows, 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
/* log_10 (2). */
#define M_LOG10_2l 0.3010299956639811952137388947244930267682L
/* pi * log10 (e). */
#define M_PI_LOG10El 1.364376353841841347485783625431355770210L
__complex__ long double
__clog10l (__complex__ long double x)
{
__complex__ long double result;
int rcls = fpclassify (__real__ x);
int icls = fpclassify (__imag__ x);
if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
{
/* Real and imaginary part are 0.0. */
__imag__ result = signbit (__real__ x) ? M_PI_LOG10El : 0.0;
__imag__ result = __copysignl (__imag__ result, __imag__ x);
/* Yes, the following line raises an exception. */
__real__ result = -1.0 / fabsl (__real__ x);
}
else if (__glibc_likely (rcls != FP_NAN && icls != FP_NAN))
{
/* Neither real nor imaginary part is NaN. */
long double absx = fabsl (__real__ x), absy = fabsl (__imag__ x);
int scale = 0;
if (absx < absy)
{
long double t = absx;
absx = absy;
absy = t;
}
if (absx > LDBL_MAX / 2.0L)
{
scale = -1;
absx = __scalbnl (absx, scale);
absy = (absy >= LDBL_MIN * 2.0L ? __scalbnl (absy, scale) : 0.0L);
}
else if (absx < LDBL_MIN && absy < LDBL_MIN)
{
scale = LDBL_MANT_DIG;
absx = __scalbnl (absx, scale);
absy = __scalbnl (absy, scale);
}
if (absx == 1.0L && scale == 0)
{
long double absy2 = absy * absy;
if (absy2 <= LDBL_MIN * 2.0L * M_LN10l)
{
long double force_underflow = absy2 * absy2;
__real__ result = absy2 * (M_LOG10El / 2.0);
math_force_eval (force_underflow);
}
else
__real__ result = __log1pl (absy2) * (M_LOG10El / 2.0L);
}
else if (absx > 1.0L && absx < 2.0L && absy < 1.0L && scale == 0)
{
long double d2m1 = (absx - 1.0L) * (absx + 1.0L);
if (absy >= LDBL_EPSILON)
d2m1 += absy * absy;
__real__ result = __log1pl (d2m1) * (M_LOG10El / 2.0L);
}
else if (absx < 1.0L
&& absx >= 0.75L
&& absy < LDBL_EPSILON / 2.0L
&& scale == 0)
{
long double d2m1 = (absx - 1.0L) * (absx + 1.0L);
__real__ result = __log1pl (d2m1) * (M_LOG10El / 2.0L);
}
else if (absx < 1.0L && (absx >= 0.75L || absy >= 0.5L) && scale == 0)
{
long double d2m1 = __x2y2m1l (absx, absy);
__real__ result = __log1pl (d2m1) * (M_LOG10El / 2.0L);
}
else
{
long double d = __ieee754_hypotl (absx, absy);
__real__ result = __ieee754_log10l (d) - scale * M_LOG10_2l;
}
__imag__ result = M_LOG10El * __ieee754_atan2l (__imag__ x, __real__ x);
}
else
{
__imag__ result = __nanl ("");
if (rcls == FP_INFINITE || icls == FP_INFINITE)
/* Real or imaginary part is infinite. */
__real__ result = HUGE_VALL;
else
__real__ result = __nanl ("");
}
return result;
}
weak_alias (__clog10l, clog10l)
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