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/* Compute complex natural logarithm.
Copyright (C) 1997-2018 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 "quadmath-imp.h"
__complex128
clogq (__complex128 x)
{
__complex128 result;
int rcls = fpclassifyq (__real__ x);
int icls = fpclassifyq (__imag__ x);
if (__glibc_unlikely (rcls == QUADFP_ZERO && icls == QUADFP_ZERO))
{
/* Real and imaginary part are 0.0. */
__imag__ result = signbitq (__real__ x) ? (__float128) M_PIq : 0;
__imag__ result = copysignq (__imag__ result, __imag__ x);
/* Yes, the following line raises an exception. */
__real__ result = -1 / fabsq (__real__ x);
}
else if (__glibc_likely (rcls != QUADFP_NAN && icls != QUADFP_NAN))
{
/* Neither real nor imaginary part is NaN. */
__float128 absx = fabsq (__real__ x), absy = fabsq (__imag__ x);
int scale = 0;
if (absx < absy)
{
__float128 t = absx;
absx = absy;
absy = t;
}
if (absx > FLT128_MAX / 2)
{
scale = -1;
absx = scalbnq (absx, scale);
absy = (absy >= FLT128_MIN * 2 ? scalbnq (absy, scale) : 0);
}
else if (absx < FLT128_MIN && absy < FLT128_MIN)
{
scale = FLT128_MANT_DIG;
absx = scalbnq (absx, scale);
absy = scalbnq (absy, scale);
}
if (absx == 1 && scale == 0)
{
__real__ result = log1pq (absy * absy) / 2;
math_check_force_underflow_nonneg (__real__ result);
}
else if (absx > 1 && absx < 2 && absy < 1 && scale == 0)
{
__float128 d2m1 = (absx - 1) * (absx + 1);
if (absy >= FLT128_EPSILON)
d2m1 += absy * absy;
__real__ result = log1pq (d2m1) / 2;
}
else if (absx < 1
&& absx >= 0.5Q
&& absy < FLT128_EPSILON / 2
&& scale == 0)
{
__float128 d2m1 = (absx - 1) * (absx + 1);
__real__ result = log1pq (d2m1) / 2;
}
else if (absx < 1
&& absx >= 0.5Q
&& scale == 0
&& absx * absx + absy * absy >= 0.5Q)
{
__float128 d2m1 = __quadmath_x2y2m1q (absx, absy);
__real__ result = log1pq (d2m1) / 2;
}
else
{
__float128 d = hypotq (absx, absy);
__real__ result = logq (d) - scale * (__float128) M_LN2q;
}
__imag__ result = atan2q (__imag__ x, __real__ x);
}
else
{
__imag__ result = nanq ("");
if (rcls == QUADFP_INFINITE || icls == QUADFP_INFINITE)
/* Real or imaginary part is infinite. */
__real__ result = HUGE_VALQ;
else
__real__ result = nanq ("");
}
return result;
}
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