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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libc/] [sys/] [linux/] [cmath/] [s_csqrt.c] - Rev 859
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/* Complex square root of double 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 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__ double __csqrt (__complex__ double x) { __complex__ double 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_VAL; __imag__ res = __imag__ x; } else if (rcls == FP_INFINITE) { if (__real__ x < 0.0) { __real__ res = icls == FP_NAN ? __nan ("") : 0; __imag__ res = __copysign (HUGE_VAL, __imag__ x); } else { __real__ res = __real__ x; __imag__ res = (icls == FP_NAN ? __nan ("") : __copysign (0.0, __imag__ x)); } } else { __real__ res = __nan (""); __imag__ res = __nan (""); } } else { if (icls == FP_ZERO) { if (__real__ x < 0.0) { __real__ res = 0.0; __imag__ res = __copysign (__ieee754_sqrt (-__real__ x), __imag__ x); } else { __real__ res = fabs (__ieee754_sqrt (__real__ x)); __imag__ res = __copysign (0.0, __imag__ x); } } else if (rcls == FP_ZERO) { double r = __ieee754_sqrt (0.5 * fabs (__imag__ x)); __real__ res = __copysign (r, __imag__ x); __imag__ res = r; } else { double d, r, s; d = __ieee754_hypot (__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_sqrt (0.5 * d + 0.5 * __real__ x); s = (0.5 * __imag__ x) / r; } else { s = __ieee754_sqrt (0.5 * d - 0.5 * __real__ x); r = fabs ((0.5 * __imag__ x) / s); } __real__ res = r; __imag__ res = __copysign (s, __imag__ x); } } return res; } weak_alias (__csqrt, csqrt) #ifdef NO_LONG_DOUBLE strong_alias (__csqrt, __csqrtl) weak_alias (__csqrt, csqrtl) #endif
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