glibc/sysdeps/libm-ieee754/s_cbrt.c
Ulrich Drepper dd7d45e838 Update.
1997-10-29 21:20  Ulrich Drepper  <drepper@cygnus.com>

	* libio/strops.c (_IO_str_seekoff): If mode is zero and the read/write
	pointers are tied set mode according to current stream mode.

	* include/features.h [_GNU_SOURCE] (_POSIX_C_SOURCE): Define to
	199506L.
	Define _XOPEN_SOURCE to 500 if _POSIX_C_SOURCE is defined.
	* manual/creature.texi: Describe this.

	* manual/socket.texi: Describe connect, accept, send, sendmsg, sendto,
	recv, recvfrom, and recvmsg as cancelation points.
	* sysdeps/unix/inet/syscalls.list: Add __libc_* names for these
	functions.

1997-10-17  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* Make-dist (try-sysdeps): Don't look for stub files anymore.

	* manual/maint.texi (Porting): Remove another reference to stub
	directory.

	* sysdeps/unix/bsd/sun/sethostid.c: Include stub version from
	generic subdir.
	* sysdeps/unix/sysv/irix4/reboot.c: Likewise.
	* sysdeps/unix/sysv/irix4/swapon.c: Likewise

1997-10-29 03:54  Ulrich Drepper  <drepper@cygnus.com>

	* resolv/nss_dns/dns-host.c: Change variable pointed to by h_errnop
	in all error cases (PR 244).

1997-10-29 00:56  Ulrich Drepper  <drepper@cygnus.com>

	* posix/glob.c: Fix handling of expressions like "*/" (PR 325).
	Optimize by using mempcpy.

1997-10-17  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* po/Makefile ($(mo-installed)): Don't fail during installation if
	files don't exist (might happen if msgfmt doesn't exist) (PR 328).
	Suggested by Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>.

1997-10-24  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* sysdeps/generic/bits/errno.h (ENOMSG): Define it.
	Pointed out by Klaus Espenlaub
	<kespenla@hydra.informatik.uni-ulm.de> (PR libc/259).

1997-10-28 17:40  Ulrich Drepper  <drepper@cygnus.com>

	* sysdeps/libm-ieee754/s_cbrt.c: Testing the returned exponent for
	zero isn't enough to determine illegal arguments.
	* sysdeps/libm-ieee754/s_cbrtf.c: Likewise.
	* sysdeps/libm-ieee754/s_cbrtl.c: Likewise.

1997-10-28 17:14  Ulrich Drepper  <drepper@cygnus.com>

	* manual/filesys.texi (S_ISVTX): Describe that it is available with
	_BSD_SOURCE only.
	Reported by Jochen Hein <jochen.hein@delphi.central.de>.

1997-10-28 04:26  Ulrich Drepper  <drepper@cygnus.com>

	* time/tzfile.c (__tzfile_compute): Use negated value of offset for
	timezone variable.
	* time/tzset.c (tz_compute): Likewise.
	Reported by Erik Troan <ewt@redhat.com>.

1997-10-28 02:51  Ulrich Drepper  <drepper@cygnus.com>

	* manual/filesys.texi: Correct prototype in readdir_r description.
	Reported by Jim Meyering <meyering@eng.ascend.com>.

1997-10-27  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* math/libm-test.c (cbrt_test): Add test for cbrt(0.970299).

1997-10-26 19:39  Zack Weinberg  <zack@rabi.phys.columbia.edu>

	* stdlib/l64a.c: Produce a useful result for n < 0.
	* stdlib/a64l.c: Use unsigned type for working variable.
	* manual/string.texi (general): Grammar, typo, overfull fixes.
	(strlen): Insert warning about sizeof(char *).
	(a64l, l64a): Make documentation agree with implementation.

	* libio/iofdopen.c: Use _IO_FILE_complete, not _IO_FILE_plus.
	* posix/unistd.h: Add prototypes for __pread, __pread64, __pwrite
1997-10-29 20:33:40 +00:00

77 lines
2.2 KiB
C

/* Compute cubic root of double value.
Copyright (C) 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Dirk Alboth <dirka@uni-paderborn.de> and
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 "math.h"
#include "math_private.h"
#define CBRT2 1.2599210498948731648 /* 2^(1/3) */
#define SQR_CBRT2 1.5874010519681994748 /* 2^(2/3) */
static const double factor[5] =
{
1.0 / SQR_CBRT2,
1.0 / CBRT2,
1.0,
CBRT2,
SQR_CBRT2
};
double
__cbrt (double x)
{
double xm, ym, u, t2;
int xe;
/* Reduce X. XM now is an range 1.0 to 0.5. */
xm = __frexp (fabs (x), &xe);
/* If X is not finite or is null return it (with raising exceptions
if necessary.
Note: *Our* version of `frexp' sets XE to zero if the argument is
Inf or NaN. This is not portable but faster. */
if (xe == 0 && fpclassify (x) <= FP_ZERO)
return x + x;
u = (0.354895765043919860
+ ((1.50819193781584896
+ ((-2.11499494167371287
+ ((2.44693122563534430
+ ((-1.83469277483613086
+ (0.784932344976639262 - 0.145263899385486377 * xm) * xm)
* xm))
* xm))
* xm))
* xm));
t2 = u * u * u;
ym = u * (t2 + 2.0 * xm) / (2.0 * t2 + xm) * factor[2 + xe % 3];
return __ldexp (x > 0.0 ? ym : -ym, xe / 3);
}
weak_alias (__cbrt, cbrt)
#ifdef NO_LONG_DOUBLE
strong_alias (__cbrt, __cbrtl)
weak_alias (__cbrt, cbrtl)
#endif