mirror of git://gcc.gnu.org/git/gcc.git
111 lines
2.9 KiB
C
111 lines
2.9 KiB
C
/* Complex square root of float value. */
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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__ float
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csqrtf (__complex__ float x)
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{
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__complex__ float res;
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if (!FINITEF_P (__real__ x) || !FINITEF_P (__imag__ x))
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{
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if (INFINITEF_P (__imag__ x))
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{
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__real__ res = HUGE_VALF;
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__imag__ res = __imag__ x;
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}
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else if (INFINITEF_P (__real__ x))
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{
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if (__real__ x < 0.0)
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{
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__real__ res = __imag__ x != __imag__ x ? NAN : 0;
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__imag__ res = copysignf (HUGE_VALF, __imag__ x);
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}
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else
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{
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__real__ res = __real__ x;
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__imag__ res = (__imag__ x != __imag__ x
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? NAN : copysignf (0.0, __imag__ x));
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}
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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
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{
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if (__imag__ x == 0.0)
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{
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if (__real__ x < 0.0)
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{
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__real__ res = 0.0;
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__imag__ res = copysignf (sqrtf (-__real__ x), __imag__ x);
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}
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else
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{
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__real__ res = fabsf (sqrtf (__real__ x));
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__imag__ res = copysignf (0.0, __imag__ x);
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}
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}
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else if (__real__ x == 0.0)
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{
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float r = sqrtf (0.5 * fabsf (__imag__ x));
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__real__ res = copysignf (r, __imag__ x);
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__imag__ res = r;
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}
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else
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{
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__complex__ float q;
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float t, r;
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if (fabsf (__imag__ x) < 2.0e-4 * fabsf (__real__ x))
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t = 0.25 * __imag__ x * (__imag__ x / __real__ x);
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else
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t = 0.5 * (hypotf (__real__ x, __imag__ x) - __real__ x);
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r = sqrtf (t);
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__real__ q = __imag__ x / (2.0 * r);
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__imag__ q = r;
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/* Heron iteration in complex arithmetic. */
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res = 0.5 * (q + q / x);
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}
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}
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return res;
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}
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