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Diffstat (limited to 'sysdeps/generic/s_csqrtf.c')
| -rw-r--r-- | sysdeps/generic/s_csqrtf.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/sysdeps/generic/s_csqrtf.c b/sysdeps/generic/s_csqrtf.c new file mode 100644 index 0000000000..3bc979f6e2 --- /dev/null +++ b/sysdeps/generic/s_csqrtf.c @@ -0,0 +1,110 @@ +/* Complex square root of float value. + Copyright (C) 1997, 1998 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <complex.h> +#include <math.h> + +#include "math_private.h" + + +__complex__ float +__csqrtf (__complex__ float x) +{ + __complex__ float res; + int rcls = fpclassify (__real__ x); + int icls = fpclassify (__imag__ x); + + if (rcls <= FP_INFINITE || icls <= FP_INFINITE) + { + 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 (icls == FP_ZERO) + { + 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 (rcls == FP_ZERO) + { + float r = __ieee754_sqrtf (0.5 * fabsf (__imag__ x)); + + __real__ res = __copysignf (r, __imag__ x); + __imag__ res = r; + } + else + { + float d, r, s; + + 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 + 0.5f * __real__ x); + s = (0.5f * __imag__ x) / r; + } + else + { + s = __ieee754_sqrtf (0.5f * d - 0.5f * __real__ x); + r = fabsf ((0.5f * __imag__ x) / s); + } + + __real__ res = r; + __imag__ res = __copysignf (s, __imag__ x); + } + } + + return res; +} +weak_alias (__csqrtf, csqrtf) |