'\" t .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk .\" .\" .\" 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 6.8" .SH NAME cos, cosf, cosl \- cosine function .SH LIBRARY Math library .RI ( libm ", " \-lm ) .SH SYNOPSIS .nf .B #include .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)