'\" t
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" 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 2002-07-27 by Walter Harms
.\" 	(walter.harms@informatik.uni-oldenburg.de)
.TH cos 3 2024-05-02 "Linux man-pages 6.9.1"
.SH NAME
cos, cosf, cosl \- cosine function
.SH LIBRARY
Math library
.RI ( libm ", " \-lm )
.SH SYNOPSIS
.nf
.B #include <math.h>
.P
.BI "double cos(double " x );
.BI "float cosf(float " x );
.BI "long double cosl(long double " x );
.fi
.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.P
.BR cosf (),
.BR cosl ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.SH DESCRIPTION
These functions return the cosine of
.IR x ,
where
.I x
is
given in radians.
.SH RETURN VALUE
On success, these functions return the cosine of
.IR x .
.P
If
.I x
is a NaN, a NaN is returned.
.P
If
.I x
is positive infinity or negative infinity,
a domain error occurs,
and a NaN is returned.
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.P
The following errors can occur:
.TP
Domain error: \fIx\fP is an infinity
.I errno
is set to
.B EDOM
(but see BUGS).
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR cos (),
.BR cosf (),
.BR cosl ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
C89, POSIX.1-2001.
.P
The variant returning
.I double
also conforms to
SVr4, 4.3BSD.
.SH BUGS
Before glibc 2.10, the glibc implementation did not set
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6780
.I errno
to
.B EDOM
when a domain error occurred.
.SH SEE ALSO
.BR acos (3),
.BR asin (3),
.BR atan (3),
.BR atan2 (3),
.BR ccos (3),
.BR sin (3),
.BR sincos (3),
.BR tan (3)