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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libc/] [sys/] [linux/] [cmath/] [s_csqrtf.c] - Blame information for rev 829

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Line No. Rev Author Line
1 207 jeremybenn
/* Complex square root of float value.
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   Copyright (C) 1997, 1998 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, 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__ float
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__csqrtf (__complex__ float x)
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{
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  __complex__ float 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 (icls == FP_INFINITE)
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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 (rcls == FP_INFINITE)
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        {
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          if (__real__ x < 0.0)
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            {
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              __real__ res = icls == FP_NAN ? __nanf ("") : 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 = (icls == FP_NAN
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                              ? __nanf ("") : __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 = __nanf ("");
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          __imag__ res = __nanf ("");
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        }
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    }
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  else
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    {
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      if (icls == FP_ZERO)
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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 (__ieee754_sqrtf (-__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 = fabsf (__ieee754_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 (rcls == FP_ZERO)
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        {
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          float r = __ieee754_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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          float d, r, s;
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          d = __ieee754_hypotf (__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 = __ieee754_sqrtf (0.5f * d + 0.5f * __real__ x);
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              s = (0.5f * __imag__ x) / r;
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            }
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          else
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            {
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              s = __ieee754_sqrtf (0.5f * d - 0.5f * __real__ x);
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              r = fabsf ((0.5f * __imag__ x) / s);
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            }
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          __real__ res = r;
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          __imag__ res = __copysignf (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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weak_alias (__csqrtf, csqrtf)

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