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SYNOPSIS: Fixed feature test macro requirements. 

Added RETURN VALUE section.
Rewrote ERRORS section.
Updated CONFORMING TO.
Added BUGS section noting that pole error sets errno to EDOM,
when it should be ERANGE instead; see also
http://sources.redhat.com/bugzilla/show_bug.cgi?id=6759.
This commit is contained in:
Michael Kerrisk 2008-08-01 05:26:01 +00:00
parent f71288ac30
commit 138b47a97e
1 changed files with 78 additions and 15 deletions
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93
man3/atanh.3
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@ -1,4 +1,6 @@
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\" <mtk.manpages@gmail.com>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
@ -28,7 +30,7 @@
.\" Modified 2002-07-27 by Walter Harms
.\" (walter.harms@informatik.uni-oldenburg.de)
.\"
.TH ATANH 3 2007-07-26 "" "Linux Programmer's Manual"
.TH ATANH 3 2008-07-29 "" "Linux Programmer's Manual"
.SH NAME
atanh, atanhf, atanhl \- inverse hyperbolic tangent function
.SH SYNOPSIS
@ -50,10 +52,13 @@ Feature Test Macro Requirements for glibc (see
.in
.sp
.ad l
.BR atanh (),
.BR atanh ():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
.I cc\ -std=c99
.br
.BR atanhf (),
.BR atanhl ():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
.I cc\ -std=c99
.ad b
.SH DESCRIPTION
@ -61,21 +66,79 @@ The
.BR atanh ()
function calculates the inverse hyperbolic tangent of
\fIx\fP; that is the value whose hyperbolic tangent is \fIx\fP.
If the absolute value of \fIx\fP is greater than 1.0,
.BR atanh ()
returns
not-a-number (NaN) and \fIerrno\fP is set.
.SH "RETURN VALUE"
On success, these functions return the inverse hyperbolic tangent of
.IR x .
If
.I x
is a NaN, a NaN is returned.
If
.I x
is +0 (\-0), +0 (\-0) is returned.
If
.I x
is +1 or \-1,
a "pole error" occurs,
and the functions return
.BR HUGE_VAL ,
.BR HUGE_VALF ,
or
.BR HUGE_VALL ,
respectively, with the mathematically correct sign.
If the absolute value of
.I x
is greater than 1,
a "domain error" occurs,
and a NaN is returned.
.\"
.\" POSIX.1-2001 documents an optional range error for subnormal x;
.\" glibc 2.8 does not do this.
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
.B EDOM
\fIx\fP is out of range.
Domain error: \fIx\fP less than \-1 or greater than +1
.I errno
is set to
.BR EDOM .
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
.TP
Pole error: \fIx\fP is +1 or \-1
.I errno
is set to
.BR ERANGE
(but see BUGS).
.\" FIXME . glibc actually gives EDOM for this case
A divide-by-zero floating-point exception
.RB ( FE_DIVBYZERO )
is raised.
.SH "CONFORMING TO"
SVr4, POSIX.1-2001, 4.3BSD, C89.
The
.I float
and
.I "long double"
variants are C99 requirements.
C99, POSIX.1-2001.
The variant returning
.I double
also conforms to
SVr4, 4.3BSD, C89.
.SH BUGS
For a pole error,
.\"
.\" FIXME . this is as at glibc 2.8; check later if this bug is fixed
.\" This can be seen in sysdeps/ieee754/k_standard.c
.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6759
.I errno
is set to
.BR EDOM ;
POSIX.1 says it should be set to
.BR ERANGE .
.SH "SEE ALSO"
.BR acosh (3),
.BR asinh (3),