| /* Complex square root of float value. |
| Copyright (C) 1997, 1998, 2005 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, 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 = r; |
| __imag__ res = __copysignf (r, __imag__ x); |
| } |
| 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; |
| } |
| #ifndef __csqrtf |
| weak_alias (__csqrtf, csqrtf) |
| #endif |