84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
/* Compute complex base 10 logarithm.
|
|
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 <complex.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
#include <float.h>
|
|
|
|
/* log_10 (2). */
|
|
#define M_LOG10_2f 0.3010299956639811952137388947244930267682f
|
|
|
|
__complex__ float
|
|
__clog10f (__complex__ float x)
|
|
{
|
|
__complex__ float result;
|
|
int rcls = fpclassify (__real__ x);
|
|
int icls = fpclassify (__imag__ x);
|
|
|
|
if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
|
|
{
|
|
/* Real and imaginary part are 0.0. */
|
|
__imag__ result = signbit (__real__ x) ? M_PI : 0.0;
|
|
__imag__ result = __copysignf (__imag__ result, __imag__ x);
|
|
/* Yes, the following line raises an exception. */
|
|
__real__ result = -1.0 / fabsf (__real__ x);
|
|
}
|
|
else if (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1))
|
|
{
|
|
/* Neither real nor imaginary part is NaN. */
|
|
float d;
|
|
int scale = 0;
|
|
|
|
if (fabsf (__real__ x) > FLT_MAX / 2.0f
|
|
|| fabsf (__imag__ x) > FLT_MAX / 2.0f)
|
|
{
|
|
scale = -1;
|
|
__real__ x = __scalbnf (__real__ x, scale);
|
|
__imag__ x = __scalbnf (__imag__ x, scale);
|
|
}
|
|
else if (fabsf (__real__ x) < FLT_MIN
|
|
&& fabsf (__imag__ x) < FLT_MIN)
|
|
{
|
|
scale = FLT_MANT_DIG;
|
|
__real__ x = __scalbnf (__real__ x, scale);
|
|
__imag__ x = __scalbnf (__imag__ x, scale);
|
|
}
|
|
|
|
d = __ieee754_hypotf (__real__ x, __imag__ x);
|
|
|
|
__real__ result = __ieee754_log10f (d) - scale * M_LOG10_2f;
|
|
__imag__ result = M_LOG10E * __ieee754_atan2f (__imag__ x, __real__ x);
|
|
}
|
|
else
|
|
{
|
|
__imag__ result = __nanf ("");
|
|
if (rcls == FP_INFINITE || icls == FP_INFINITE)
|
|
/* Real or imaginary part is infinite. */
|
|
__real__ result = HUGE_VALF;
|
|
else
|
|
__real__ result = __nanf ("");
|
|
}
|
|
|
|
return result;
|
|
}
|
|
#ifndef __clog10f
|
|
weak_alias (__clog10f, clog10f)
|
|
#endif
|