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[thirdparty/man-pages.git] / man3 / cosh.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
.\" Modified 1996-06-08 by aeb
.\" Modified 2002-07-27 by Walter Harms
.\" (walter.harms@informatik.uni-oldenburg.de)
.\"
.TH COSH 3 2010-09-20 ""  "Linux Programmer's Manual"
.SH NAME
cosh, coshf, coshl \- hyperbolic cosine function
.SH SYNOPSIS
.nf
.B #include <math.h>
.sp
.BI "double cosh(double " x );
.br
.BI "float coshf(float " x );
.br
.BI "long double coshl(long double " x );
.fi
.sp
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR coshf (),
.BR coshl ():
.RS 4
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad
.SH DESCRIPTION
The
.BR cosh ()
function returns the hyperbolic cosine of \fIx\fP, which
is defined mathematically as:
.nf

    cosh(x) = (exp(x) + exp(\-x)) / 2
.fi
.SH RETURN VALUE
On success, these functions return the hyperbolic cosine of
.IR x .

If
.I x
is a NaN, a NaN is returned.

If
.I x
is +0 or \-0, 1 is returned.

If
.I x
is positive infinity or negative infinity,
positive infinity is returned.

If the result overflows,
a range error occurs,
and the functions return
.RB + HUGE_VAL ,
.RB + HUGE_VALF ,
or
.RB + HUGE_VALL ,
respectively.
.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
Range error: result overflow
.I errno
is set to
.BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.SH CONFORMING TO
C99, POSIX.1-2001.
The variant returning
.I double
also conforms to
SVr4, 4.3BSD.
.SH BUGS
In glibc version 2.3.4 and earlier,
an overflow floating-point
.RB ( FE_OVERFLOW  )
exception is not raised when an overflow occurs.
.SH SEE ALSO
.BR acosh (3),
.BR asinh (3),
.BR atanh (3),
.BR ccos (3),
.BR sinh (3),
.BR tanh (3)