diff options
| author | Ulrich Drepper <drepper@redhat.com> | 1998-07-29 12:34:57 +0000 |
|---|---|---|
| committer | Ulrich Drepper <drepper@redhat.com> | 1998-07-29 12:34:57 +0000 |
| commit | ec986e237a6c0fe52f172c254d3da2ef57b85eb2 (patch) | |
| tree | b938227b19ad155bf8c5b5a9960b0ebba90c80a5 /sysdeps/libm-ieee754/s_csqrt.c | |
| parent | ceeeaa3dcf76e7bc68ad276a1a54d988bef58934 (diff) | |
Update.
1998-07-29 Andreas Jaeger <aj@arthur.rhein-neckar.de>
* manual/pattern.texi (More Flags for Globbing): Fix typo.
* manual/math.texi (Special Functions): Fix typo.
* sysdeps/unix/sysv/linux/bits/in.h (IPV6_ROUTER_ALERT): New
constant from Linux 2.1.112.
* posix/Makefile (install-lib): Compile libposix.a only if
build-static == yes.
1998-07-28 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/generic/glob.c: Maintain const correctness. Move extern
declarations to file level. Cope with unsupported
_SC_GETPW_R_SIZE_MAX.
1998-07-29 Ulrich Drepper <drepper@cygnus.com>
* stdio-common/tst-printf.c: %z is now recognized by printf.
* sysdeps/libm-ieee754/c_csqrt.c: Fix problems with some cancelation
errors.
* sysdeps/libm-ieee754/c_csqrtf.c: Likewise.
* sysdeps/libm-ieee754/c_csqrtlc: Likewise.
Patch by Stephen L Moshier <moshier@mediaone.net>.
* math/libm-test.c (csqrt_test): Correct typo in one test, add
another one.
* sysdeps/unix/sysv/linux/bits/siginfo.h: Adjust siginfo_t after
latest kernel change.
Diffstat (limited to 'sysdeps/libm-ieee754/s_csqrt.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_csqrt.c | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/sysdeps/libm-ieee754/s_csqrt.c b/sysdeps/libm-ieee754/s_csqrt.c index cda23c702d..ae106bdad8 100644 --- a/sysdeps/libm-ieee754/s_csqrt.c +++ b/sysdeps/libm-ieee754/s_csqrt.c @@ -1,5 +1,5 @@ /* Complex square root of double value. - Copyright (C) 1997 Free Software Foundation, Inc. + 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. @@ -84,22 +84,25 @@ __csqrt (__complex__ double x) } else { -#if 0 /* FIXME: this is broken. */ - __complex__ double q; - double t, r; +#if 0 + double d, r, s; - if (fabs (__imag__ x) < 2.0e-4 * fabs (__real__ x)) - t = 0.25 * __imag__ x * (__imag__ x / __real__ x); + 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 - t = 0.5 * (__ieee754_hypot (__real__ x, __imag__ x) - __real__ x); - - r = __ieee754_sqrt (t); - - __real__ q = __imag__ x / (2.0 * r); - __imag__ q = r; + { + s = __ieee754_sqrt (0.5 * d - 0.5 * __real__ x); + r = (0.5 * __imag__ x) / s; + } - /* Heron iteration in complex arithmetic. */ - res = 0.5 * (q + q / x); + __real__ res = r; + __imag__ res = __copysign (s, __imag__ x); #else double d, imag; |