1/* Compute complex natural logarithm.
2   Copyright (C) 1997 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
5
6   The GNU C Library is free software; you can redistribute it and/or
7   modify it under the terms of the GNU Lesser General Public
8   License as published by the Free Software Foundation; either
9   version 2.1 of the License, or (at your option) any later version.
10
11   The GNU C Library is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   Lesser General Public License for more details.
15
16   You should have received a copy of the GNU Lesser General Public
17   License along with the GNU C Library; if not, write to the Free
18   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19   02111-1307 USA.  */
20
21#include <complex.h>
22#include <math.h>
23
24#include "math_private.h"
25
26
27__complex__ double
28__clog (__complex__ double x)
29{
30  __complex__ double result;
31  int rcls = fpclassify (__real__ x);
32  int icls = fpclassify (__imag__ x);
33
34  if (rcls == FP_ZERO && icls == FP_ZERO)
35    {
36      /* Real and imaginary part are 0.0.  */
37      __imag__ result = signbit (__real__ x) ? M_PI : 0.0;
38      __imag__ result = copysign (__imag__ result, __imag__ x);
39      /* Yes, the following line raises an exception.  */
40      __real__ result = -1.0 / fabs (__real__ x);
41    }
42  else if (rcls != FP_NAN && icls != FP_NAN)
43    {
44      /* Neither real nor imaginary part is NaN.  */
45      __real__ result = log (hypot (__real__ x,
46							__imag__ x));
47      __imag__ result = atan2 (__imag__ x, __real__ x);
48    }
49  else
50    {
51      __imag__ result = nan ("");
52      if (rcls == FP_INFINITE || icls == FP_INFINITE)
53	/* Real or imaginary part is infinite.  */
54	__real__ result = HUGE_VAL;
55      else
56	__real__ result = nan ("");
57    }
58
59  return result;
60}
61weak_alias (__clog, clog)
62#ifdef NO_LONG_DOUBLE
63strong_alias (__clog, __clogl)
64weak_alias (__clog, clogl)
65#endif
66