mirror of
https://sourceware.org/git/glibc.git
synced 2025-11-03 20:53:13 +03:00
117 lines
3.2 KiB
C
117 lines
3.2 KiB
C
/* Compute complex natural logarithm.
|
|
Copyright (C) 1997-2020 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <complex.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
#include <math-underflow.h>
|
|
#include <float.h>
|
|
|
|
CFLOAT
|
|
M_DECL_FUNC (__clog) (CFLOAT x)
|
|
{
|
|
CFLOAT 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) ? (FLOAT) M_MLIT (M_PI) : 0;
|
|
__imag__ result = M_COPYSIGN (__imag__ result, __imag__ x);
|
|
/* Yes, the following line raises an exception. */
|
|
__real__ result = -1 / M_FABS (__real__ x);
|
|
}
|
|
else if (__glibc_likely (rcls != FP_NAN && icls != FP_NAN))
|
|
{
|
|
/* Neither real nor imaginary part is NaN. */
|
|
FLOAT absx = M_FABS (__real__ x), absy = M_FABS (__imag__ x);
|
|
int scale = 0;
|
|
|
|
if (absx < absy)
|
|
{
|
|
FLOAT t = absx;
|
|
absx = absy;
|
|
absy = t;
|
|
}
|
|
|
|
if (absx > M_MAX / 2)
|
|
{
|
|
scale = -1;
|
|
absx = M_SCALBN (absx, scale);
|
|
absy = (absy >= M_MIN * 2 ? M_SCALBN (absy, scale) : 0);
|
|
}
|
|
else if (absx < M_MIN && absy < M_MIN)
|
|
{
|
|
scale = M_MANT_DIG;
|
|
absx = M_SCALBN (absx, scale);
|
|
absy = M_SCALBN (absy, scale);
|
|
}
|
|
|
|
if (absx == 1 && scale == 0)
|
|
{
|
|
__real__ result = M_LOG1P (absy * absy) / 2;
|
|
math_check_force_underflow_nonneg (__real__ result);
|
|
}
|
|
else if (absx > 1 && absx < 2 && absy < 1 && scale == 0)
|
|
{
|
|
FLOAT d2m1 = (absx - 1) * (absx + 1);
|
|
if (absy >= M_EPSILON)
|
|
d2m1 += absy * absy;
|
|
__real__ result = M_LOG1P (d2m1) / 2;
|
|
}
|
|
else if (absx < 1
|
|
&& absx >= M_LIT (0.5)
|
|
&& absy < M_EPSILON / 2
|
|
&& scale == 0)
|
|
{
|
|
FLOAT d2m1 = (absx - 1) * (absx + 1);
|
|
__real__ result = M_LOG1P (d2m1) / 2;
|
|
}
|
|
else if (absx < 1
|
|
&& absx >= M_LIT (0.5)
|
|
&& scale == 0
|
|
&& absx * absx + absy * absy >= M_LIT (0.5))
|
|
{
|
|
FLOAT d2m1 = M_SUF (__x2y2m1) (absx, absy);
|
|
__real__ result = M_LOG1P (d2m1) / 2;
|
|
}
|
|
else
|
|
{
|
|
FLOAT d = M_HYPOT (absx, absy);
|
|
__real__ result = M_LOG (d) - scale * (FLOAT) M_MLIT (M_LN2);
|
|
}
|
|
|
|
__imag__ result = M_ATAN2 (__imag__ x, __real__ x);
|
|
}
|
|
else
|
|
{
|
|
__imag__ result = M_NAN;
|
|
if (rcls == FP_INFINITE || icls == FP_INFINITE)
|
|
/* Real or imaginary part is infinite. */
|
|
__real__ result = M_HUGE_VAL;
|
|
else
|
|
__real__ result = M_NAN;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
declare_mgen_alias (__clog, clog)
|