mirror of git://gcc.gnu.org/git/gcc.git
144 lines
3.7 KiB
C
144 lines
3.7 KiB
C
/* Complex square root of __float128 value.
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Copyright (C) 1997-2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Based on an algorithm by Stephen L. Moshier <moshier@world.std.com>.
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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, see
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<http://www.gnu.org/licenses/>. */
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#include "quadmath-imp.h"
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#ifdef HAVE_FENV_H
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# include <fenv.h>
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#endif
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__complex128
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csqrtq (__complex128 x)
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{
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__complex128 res;
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int rcls = fpclassifyq (__real__ x);
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int icls = fpclassifyq (__imag__ x);
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if (__builtin_expect (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE, 0))
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{
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if (icls == QUADFP_INFINITE)
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{
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__real__ res = HUGE_VALQ;
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__imag__ res = __imag__ x;
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}
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else if (rcls == QUADFP_INFINITE)
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{
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if (__real__ x < 0.0Q)
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{
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__real__ res = icls == QUADFP_NAN ? nanq ("") : 0;
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__imag__ res = copysignq (HUGE_VALQ, __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 = (icls == QUADFP_NAN
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? nanq ("") : copysignq (0.0Q, __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 = nanq ("");
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__imag__ res = nanq ("");
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}
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}
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else
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{
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if (__builtin_expect (icls == QUADFP_ZERO, 0))
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{
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if (__real__ x < 0.0Q)
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{
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__real__ res = 0.0Q;
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__imag__ res = copysignq (sqrtq (-__real__ x),
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__imag__ x);
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}
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else
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{
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__real__ res = fabsq (sqrtq (__real__ x));
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__imag__ res = copysignq (0.0Q, __imag__ x);
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}
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}
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else if (__builtin_expect (rcls == QUADFP_ZERO, 0))
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{
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__float128 r;
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if (fabsq (__imag__ x) >= 2.0Q * FLT128_MIN)
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r = sqrtq (0.5Q * fabsq (__imag__ x));
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else
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r = 0.5Q * sqrtq (2.0Q * fabsq (__imag__ x));
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__real__ res = r;
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__imag__ res = copysignq (r, __imag__ x);
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}
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else
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{
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__float128 d, r, s;
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int scale = 0;
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if (fabsq (__real__ x) > FLT128_MAX / 4.0Q)
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{
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scale = 1;
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__real__ x = scalbnq (__real__ x, -2 * scale);
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__imag__ x = scalbnq (__imag__ x, -2 * scale);
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}
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else if (fabsq (__imag__ x) > FLT128_MAX / 4.0Q)
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{
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scale = 1;
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if (fabsq (__real__ x) >= 4.0Q * FLT128_MIN)
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__real__ x = scalbnq (__real__ x, -2 * scale);
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else
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__real__ x = 0.0Q;
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__imag__ x = scalbnq (__imag__ x, -2 * scale);
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}
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else if (fabsq (__real__ x) < FLT128_MIN
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&& fabsq (__imag__ x) < FLT128_MIN)
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{
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scale = -(FLT128_MANT_DIG / 2);
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__real__ x = scalbnq (__real__ x, -2 * scale);
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__imag__ x = scalbnq (__imag__ x, -2 * scale);
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}
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d = hypotq (__real__ x, __imag__ x);
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/* Use the identity 2 Re res Im res = Im x
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to avoid cancellation error in d +/- Re x. */
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if (__real__ x > 0)
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{
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r = sqrtq (0.5Q * (d + __real__ x));
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s = 0.5Q * (__imag__ x / r);
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}
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else
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{
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s = sqrtq (0.5Q * (d - __real__ x));
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r = fabsq (0.5Q * (__imag__ x / s));
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}
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if (scale)
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{
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r = scalbnq (r, scale);
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s = scalbnq (s, scale);
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}
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__real__ res = r;
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__imag__ res = copysignq (s, __imag__ x);
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}
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}
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return res;
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}
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