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authorUlrich Drepper <drepper@redhat.com>2005-12-14 15:06:39 +0000
committerUlrich Drepper <drepper@redhat.com>2005-12-14 15:06:39 +0000
commit9d13fb2413921c713f83efe331e8e4d219c62c6b (patch)
tree2d44d7ac45ab2d147eb8361bbff880c365aa8ad5 /math/s_csqrt.c
parentb6ab06cef4670e02756bcdd4d2c33a49369a4346 (diff)
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Moved to csu/errno-loc.c.
Diffstat (limited to 'math/s_csqrt.c')
-rw-r--r--math/s_csqrt.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/math/s_csqrt.c b/math/s_csqrt.c
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+/* Complex square root of double 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__ 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 = r;
+ __imag__ res = __copysign (r, __imag__ x);
+ }
+ 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