64 lines
2.3 KiB
C
64 lines
2.3 KiB
C
/* Compute complex natural logarithm. */
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/* Copyright (C) 1997-1999 Free Software Foundation, Inc.
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This file is part of the GNU ISO C++ Library. This library is free
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software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option)
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any later version.
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This 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this library; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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USA.
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As a special exception, you may use this file as part of a free software
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library without restriction. Specifically, if other files instantiate
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templates or use macros or inline functions from this file, or you compile
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this file and link it with other files to produce an executable, this
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file does not by itself cause the resulting executable to be covered by
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the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License. */
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#include <math.h>
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#include "mathconf.h"
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__complex__ double
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c_log (__complex__ double x)
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{
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__complex__ double result;
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if (x == 0.0)
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{
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/* Real and imaginary part are 0.0. */
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__imag__ result = signbit (__real__ x) ? M_PI : 0.0;
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__imag__ result = copysign (__imag__ result, __imag__ x);
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/* Yes, the following line raises an exception. */
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__real__ result = -1.0 / fabs (__real__ x);
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}
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else if (__real__ x == __real__ x && __imag__ x == __imag__ x)
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{
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/* Neither real nor imaginary part is NaN. */
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__real__ result = log (hypot (__real__ x, __imag__ x));
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__imag__ result = atan2 (__imag__ x, __real__ x);
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}
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else
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{
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__imag__ result = NAN;
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if (INFINITE_P (__real__ x) || INFINITE_P (__imag__ x))
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/* Real or imaginary part is infinite. */
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__real__ result = HUGE_VAL;
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else
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__real__ result = NAN;
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}
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return result;
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}
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