90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
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/* Return arc tangent of complex 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 Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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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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__catan (__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 (rcls == FP_INFINITE)
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{
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__real__ res = __copysign (M_PI_2, __real__ x);
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__imag__ res = __copysign (0.0, __imag__ x);
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}
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else if (icls == FP_INFINITE)
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{
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if (rcls >= FP_ZERO)
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__real__ res = __copysign (M_PI_2, __real__ x);
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else
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__real__ res = __nan ("");
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__imag__ res = __copysign (0.0, __imag__ x);
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}
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else if (icls == FP_ZERO || icls == FP_INFINITE)
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{
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__real__ res = __nan ("");
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__imag__ res = __copysign (0.0, __imag__ x);
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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 r2, num, den;
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r2 = __real__ x * __real__ x;
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den = 1 - r2 - __imag__ x * __imag__ x;
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__real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den);
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num = __imag__ x + 1.0;
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num = r2 + num * num;
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den = __imag__ x - 1.0;
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den = r2 + den * den;
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__imag__ res = 0.25 * __ieee754_log (num / den);
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}
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return res;
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}
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weak_alias (__catan, catan)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__catan, __catanl)
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weak_alias (__catan, catanl)
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#endif
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