glibc/math/s_clogl.c
2012-03-19 20:14:26 +00:00

79 lines
2.5 KiB
C

/* Compute complex natural 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>
__complex__ long double
__clogl (__complex__ long double x)
{
__complex__ long double 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_PIl : 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 (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1))
{
/* Neither real nor imaginary part is NaN. */
long double d;
int scale = 0;
if (fabsl (__real__ x) > LDBL_MAX / 2.0L
|| fabsl (__imag__ x) > LDBL_MAX / 2.0L)
{
scale = -1;
__real__ x = __scalbnl (__real__ x, scale);
__imag__ x = __scalbnl (__imag__ x, scale);
}
else if (fabsl (__real__ x) < LDBL_MIN
&& fabsl (__imag__ x) < LDBL_MIN)
{
scale = LDBL_MANT_DIG;
__real__ x = __scalbnl (__real__ x, scale);
__imag__ x = __scalbnl (__imag__ x, scale);
}
d = __ieee754_hypotl (__real__ x, __imag__ x);
__real__ result = __ieee754_logl (d) - scale * M_LN2l;
__imag__ result = __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 (__clogl, clogl)