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85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
/* Return arc hyperbole tangent for double value.
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Copyright (C) 1997 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <complex.h>
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#include <math.h>
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#include "math_private.h"
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__complex__ double
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__catanh (__complex__ double x)
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{
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__complex__ double res;
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int rcls = fpclassify (__real__ x);
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int icls = fpclassify (__imag__ x);
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if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
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{
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if (icls == FP_INFINITE)
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{
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__real__ res = __copysign (0.0, __real__ x);
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__imag__ res = __copysign (M_PI_2, __imag__ x);
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}
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else if (rcls == FP_INFINITE || rcls == FP_ZERO)
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{
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__real__ res = __copysign (0.0, __real__ x);
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if (icls >= FP_ZERO)
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__imag__ res = __copysign (M_PI_2, __imag__ x);
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else
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__imag__ res = __nan ("");
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}
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else
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{
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__real__ res = __nan ("");
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__imag__ res = __nan ("");
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}
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}
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else if (rcls == FP_ZERO && icls == FP_ZERO)
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{
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res = x;
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}
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else
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{
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double i2, num, den;
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i2 = __imag__ x * __imag__ x;
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num = 1.0 + __real__ x;
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num = i2 + num * num;
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den = 1.0 - __real__ x;
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den = i2 + den * den;
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__real__ res = 0.25 * (__ieee754_log (num) - __ieee754_log (den));
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den = 1 - __real__ x * __real__ x - i2;
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__imag__ res = 0.5 * __ieee754_atan2 (2.0 * __imag__ x, den);
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}
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return res;
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}
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weak_alias (__catanh, catanh)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__catanh, __catanhl)
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weak_alias (__catanh, catanhl)
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#endif
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