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/* Complex tangent function for double.
Copyright (C) 1997, 2005 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 <fenv.h>
#include <math.h>
#include <math_private.h>
__complex__ double
__ctan (__complex__ double x)
{
__complex__ double res;
if (!isfinite (__real__ x) || !isfinite (__imag__ x))
{
if (__isinf (__imag__ x))
{
__real__ res = __copysign (0.0, __real__ x);
__imag__ res = __copysign (1.0, __imag__ x);
}
else if (__real__ x == 0.0)
{
res = x;
}
else
{
__real__ res = __nan ("");
__imag__ res = __nan ("");
#ifdef FE_INVALID
if (__isinf (__real__ x))
feraiseexcept (FE_INVALID);
#endif
}
}
else
{
double sin2rx, cos2rx;
double den;
__sincos (2.0 * __real__ x, &sin2rx, &cos2rx);
den = cos2rx + __ieee754_cosh (2.0 * __imag__ x);
if (den == 0.0)
{
__complex__ double ez = __cexp (1.0i * x);
__complex__ double emz = __cexp (-1.0i * x);
res = (ez - emz) / (ez + emz) * -1.0i;
}
else
{
__real__ res = sin2rx / den;
__imag__ res = __ieee754_sinh (2.0 * __imag__ x) / den;
}
}
return res;
}
weak_alias (__ctan, ctan)
#ifdef NO_LONG_DOUBLE
strong_alias (__ctan, __ctanl)
weak_alias (__ctan, ctanl)
#endif
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