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/* Complex square root of float value.
Copyright (C) 1997-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Based on an algorithm by Stephen L. Moshier <moshier@world.std.com>.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <complex.h>
#include <math.h>
#include <math_private.h>
#include <float.h>
__complex__ float
__csqrtf (__complex__ float x)
{
__complex__ float res;
int rcls = fpclassify (__real__ x);
int icls = fpclassify (__imag__ x);
if (__builtin_expect (rcls <= FP_INFINITE || icls <= FP_INFINITE, 0))
{
if (icls == FP_INFINITE)
{
__real__ res = HUGE_VALF;
__imag__ res = __imag__ x;
}
else if (rcls == FP_INFINITE)
{
if (__real__ x < 0.0)
{
__real__ res = icls == FP_NAN ? __nanf ("") : 0;
__imag__ res = __copysignf (HUGE_VALF, __imag__ x);
}
else
{
__real__ res = __real__ x;
__imag__ res = (icls == FP_NAN
? __nanf ("") : __copysignf (0.0, __imag__ x));
}
}
else
{
__real__ res = __nanf ("");
__imag__ res = __nanf ("");
}
}
else
{
if (__builtin_expect (icls == FP_ZERO, 0))
{
if (__real__ x < 0.0)
{
__real__ res = 0.0;
__imag__ res = __copysignf (__ieee754_sqrtf (-__real__ x),
__imag__ x);
}
else
{
__real__ res = fabsf (__ieee754_sqrtf (__real__ x));
__imag__ res = __copysignf (0.0, __imag__ x);
}
}
else if (__builtin_expect (rcls == FP_ZERO, 0))
{
float r;
if (fabsf (__imag__ x) >= 2.0f * FLT_MIN)
r = __ieee754_sqrtf (0.5f * fabsf (__imag__ x));
else
r = 0.5f * __ieee754_sqrtf (2.0f * fabsf (__imag__ x));
__real__ res = r;
__imag__ res = __copysignf (r, __imag__ x);
}
else
{
float d, r, s;
int scale = 0;
if (fabsf (__real__ x) > FLT_MAX / 4.0f)
{
scale = 1;
__real__ x = __scalbnf (__real__ x, -2 * scale);
__imag__ x = __scalbnf (__imag__ x, -2 * scale);
}
else if (fabsf (__imag__ x) > FLT_MAX / 4.0f)
{
scale = 1;
if (fabsf (__real__ x) >= 4.0f * FLT_MIN)
__real__ x = __scalbnf (__real__ x, -2 * scale);
else
__real__ x = 0.0f;
__imag__ x = __scalbnf (__imag__ x, -2 * scale);
}
else if (fabsf (__real__ x) < FLT_MIN
&& fabsf (__imag__ x) < FLT_MIN)
{
scale = -(FLT_MANT_DIG / 2);
__real__ x = __scalbnf (__real__ x, -2 * scale);
__imag__ x = __scalbnf (__imag__ x, -2 * scale);
}
d = __ieee754_hypotf (__real__ x, __imag__ x);
/* Use the identity 2 Re res Im res = Im x
to avoid cancellation error in d +/- Re x. */
if (__real__ x > 0)
{
r = __ieee754_sqrtf (0.5f * (d + __real__ x));
s = 0.5f * (__imag__ x / r);
}
else
{
s = __ieee754_sqrtf (0.5f * (d - __real__ x));
r = fabsf (0.5f * (__imag__ x / s));
}
if (scale)
{
r = __scalbnf (r, scale);
s = __scalbnf (s, scale);
}
__real__ res = r;
__imag__ res = __copysignf (s, __imag__ x);
}
}
return res;
}
#ifndef __csqrtf
weak_alias (__csqrtf, csqrtf)
#endif
|
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