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/* Compute complex natural logarithm.

   Copyright (C) 1997 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, write to the Free

   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA

   02111-1307 USA.  */

#include <complex.h>

#include <math.h>

#include "math_private.h"

__complex__ double

__clog (__complex__ double x)

{

  __complex__ double result;

  int rcls = fpclassify (__real__ x);

  int icls = fpclassify (__imag__ x);

  if (rcls == FP_ZERO && icls == FP_ZERO)

    {

      /* Real and imaginary part are 0.0.  */

      __imag__ result = signbit (__real__ x) ? M_PI : 0.0;

      __imag__ result = __copysign (__imag__ result, __imag__ x);

      /* Yes, the following line raises an exception.  */

      __real__ result = -1.0 / fabs (__real__ x);

    }

  else if (rcls != FP_NAN && icls != FP_NAN)

    {

      /* Neither real nor imaginary part is NaN.  */

      __real__ result = __ieee754_log (__ieee754_hypot (__real__ x,

                                                        __imag__ x));

      __imag__ result = __ieee754_atan2 (__imag__ x, __real__ x);

    }

  else

    {

      __imag__ result = __nan ("");

      if (rcls == FP_INFINITE || icls == FP_INFINITE)

        /* Real or imaginary part is infinite.  */

        __real__ result = HUGE_VAL;

      else

        __real__ result = __nan ("");

    }

  return result;

}

weak_alias (__clog, clog)

#ifdef NO_LONG_DOUBLE

strong_alias (__clog, __clogl)

weak_alias (__clog, clogl)

#endif