The man pages for cacos(), cacosh(), catan(), catanh()
contain incorrect formulae describing the functions.
As reported by Richard B. Kreckel:
cacos, cacosf, cacosl:
The formula given in the man page
cacos(z) = -i clog(z + csqrt(z * z - 1))
gives wrong results in second and fourth quadrant of
complex plain.
The formula
cacos(z) = -i clog(z + I*csqrt(1 - z * z))
gives correct results.
catan, catanf, catanl:
The formula given in the man page
catan(z) = 1 / 2i clog((1 + iz) / (1 - iz))
gives wrong results on the negative imaginary axis beginning
at -I (along one of the two branch cuts). Besides, the formula
is written in an ambiguous way.
The formula
catan(z) = (clog(1 + iz) - clog(1 - iz)) / 2i
gives correct results.
cacosh, cacoshf, cacoshl:
The formula given in the man page
cacosh(z) = (0.5) * clog((1 + z) / (1 - z))
gives wrong results everywhere in the complex plain.
(The formula seems to be copied from the one for catanh,
where it is sometimes correct.)
The formula
cacosh(z) = 2 * clog(csqrt((z + 1)/2) + csqrt((z - 1)/2))
gives correct results.
catanh, catanhf, catanhl:
The formula given in the man page
catanh(z) = 0.5 * clog((1 + z) / (1 - z))
gives wrong results on the positive real axis beginning at 1
(along one of the two branch cuts).
The formula
catanh(z) = 0.5 * (clog(1 + z) - clog(1 - z))
gives correct results.
I've also checked casin, casinf, casinl, casinh, casinhf, and
casinhl and the formulae given there
casin(z) = -i clog(iz + csqrt(1 - z * z))
casinh(z) = clog(z + csqrt(z * z + 1))
are actually correct.
Reported-by: Richard B. Kreckel <kreckel@ginac.de>
Reviewed-by: Andries Brouwer <Andries.Brouwer@cwi.nl>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The current version of the page says (under ERRORS):
> EBUSY (not on Linux)
> The file pathname cannot be unlinked because it is being
> used by the system or another process and the
> implementation considers this an error.
But if you look in the kernel source file fs/namei.c
at routine may_delete() you'll see two occasions where
an EBUSY is generated. So the above "not on Linux" is wrong.
I suggest that this '(not on Linux)' be removed. It may
also improve the page if the commentary is reworded to give a
better description of the two situations. Something along
the lines of:
> The file pathname cannot be unlinked because it is being used
> by the system, e.g. if some (relative) rootdir is mounted upon it,
> or because the NFS client software created it to represent an
> active but otherwise nameless inode ("NFS silly renamed").
Just FYI: the NFS silly rename (you'll find this term mentioned
in the kernel source code) is described at:
http://nfs.sourceforge.net/#section_d
under section D2. The reason I found this manpage bug is because
I stumbled upon one of these silly renamed files, and an strace
of the rm-command revealed the EBUSY return errno.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Linux 3.0 (commit f8df13e0a901fe55631fed66562369b4dba40f8b)
implements \E[3J to allow scrambling content of console
including scroll-back buffer
(http://thread.gmane.org/gmane.linux.kernel/1125792).
This is useful at terminal lock to disallow attacker to scroll
visible window back and to see sensitive data. Other \E[J sequences
do not blank history.
\E[3J is superset of \E[2J. In other words, it clears visible screen too.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
See http://bugs.debian.org/cgi-bin/bugreport.cgi?641513
timerfd_settime(2) states that "The old_value argument returns a
structure containing the setting of the timer that was current at
the time of the call"; however, it does not mention that the
caller can pass NULL to ignore that value. Only the example
shows that the caller can pass NULL.
Reported-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Linux kernel commit cc56f7de7f00d188c7c4da1e9861581853b9e92f
meant sendfile(2) can work with any output file.
Therefore the 'out_fd' of sendfile(2) can refer to any file
(since Linux 2.6.33).
Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
As noted in the DESCRIPTION, the file descriptor must be writable
in order to place a lock.
Reported-by: Mikel Ward <mikel@mikelward.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Since glibc 2.3, resolved_path can be non-NULL (with the
semantics already documented in the page).
Reported-by: Seonghun Lim <wariua@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In the second paragraph of DESCRIPTION section, one of the
sources of error messages is incorrect: the four functions obtain
error message only from errno, and "a code" is just relevant
with errc() and warnc(), which are not present on Linux.
see http://www.unix.com/man-page/freebsd/3/ERR/ .
Then, the third paragraph becomes a duplicate.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk