mirror of
https://github.com/autc04/Retro68.git
synced 2024-12-28 14:31:50 +00:00
117 lines
3.5 KiB
C
117 lines
3.5 KiB
C
/* Compute complex base 10 logarithm for complex __float128.
|
|
Copyright (C) 1997-2012 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"
|
|
|
|
|
|
/* log_10 (2). */
|
|
#define M_LOG10_2q 0.3010299956639811952137388947244930267682Q
|
|
|
|
|
|
__complex128
|
|
clog10q (__complex128 x)
|
|
{
|
|
__complex128 result;
|
|
int rcls = fpclassifyq (__real__ x);
|
|
int icls = fpclassifyq (__imag__ x);
|
|
|
|
if (__builtin_expect (rcls == QUADFP_ZERO && icls == QUADFP_ZERO, 0))
|
|
{
|
|
/* Real and imaginary part are 0.0. */
|
|
__imag__ result = signbitq (__real__ x) ? M_PIq : 0.0Q;
|
|
__imag__ result = copysignq (__imag__ result, __imag__ x);
|
|
/* Yes, the following line raises an exception. */
|
|
__real__ result = -1.0Q / fabsq (__real__ x);
|
|
}
|
|
else if (__builtin_expect (rcls != QUADFP_NAN && icls != QUADFP_NAN, 1))
|
|
{
|
|
/* 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 / 2.0Q)
|
|
{
|
|
scale = -1;
|
|
absx = scalbnq (absx, scale);
|
|
absy = (absy >= FLT128_MIN * 2.0Q ? scalbnq (absy, scale) : 0.0Q);
|
|
}
|
|
else if (absx < FLT128_MIN && absy < FLT128_MIN)
|
|
{
|
|
scale = FLT128_MANT_DIG;
|
|
absx = scalbnq (absx, scale);
|
|
absy = scalbnq (absy, scale);
|
|
}
|
|
|
|
if (absx == 1.0Q && scale == 0)
|
|
{
|
|
__float128 absy2 = absy * absy;
|
|
if (absy2 <= FLT128_MIN * 2.0Q * M_LN10q)
|
|
__real__ result
|
|
= (absy2 / 2.0Q - absy2 * absy2 / 4.0Q) * M_LOG10Eq;
|
|
else
|
|
__real__ result = log1pq (absy2) * (M_LOG10Eq / 2.0Q);
|
|
}
|
|
else if (absx > 1.0Q && absx < 2.0Q && absy < 1.0Q && scale == 0)
|
|
{
|
|
__float128 d2m1 = (absx - 1.0Q) * (absx + 1.0Q);
|
|
if (absy >= FLT128_EPSILON)
|
|
d2m1 += absy * absy;
|
|
__real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
|
|
}
|
|
else if (absx < 1.0Q
|
|
&& absx >= 0.75Q
|
|
&& absy < FLT128_EPSILON / 2.0Q
|
|
&& scale == 0)
|
|
{
|
|
__float128 d2m1 = (absx - 1.0Q) * (absx + 1.0Q);
|
|
__real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
|
|
}
|
|
else if (absx < 1.0Q && (absx >= 0.75Q || absy >= 0.5Q) && scale == 0)
|
|
{
|
|
__float128 d2m1 = __quadmath_x2y2m1q (absx, absy);
|
|
__real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
|
|
}
|
|
else
|
|
{
|
|
__float128 d = hypotq (absx, absy);
|
|
__real__ result = log10q (d) - scale * M_LOG10_2q;
|
|
}
|
|
|
|
__imag__ result = M_LOG10Eq * 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;
|
|
}
|