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NAME

       cos, cosf, cosl - cosine function

SYNOPSIS

       #include <math.h>

       double cos(double x);
       float cosf(float x);
       long double cosl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       cosf(), cosl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

DESCRIPTION

       The cos() function returns the cosine of x, where x is given in radians.

RETURN VALUE

       On success, these functions return the cosine of x.

       If x is a NaN, a NaN is returned.

       If x is positive infinity or negative infinity, a  domain  error  occurs,  and  a  NaN  is
       returned.

ERRORS

       See  math_error(7)  for information on how to determine whether an error has occurred when
       calling these functions.

       The following errors can occur:

       Domain error: x is an infinity
              errno is  set  to  EDOM  (but  see  BUGS).   An  invalid  floating-point  exception
              (FE_INVALID) is raised.

CONFORMING TO

       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4, 4.3BSD.

BUGS

       Before  version  2.10,  the  glibc  implementation did not set errno to EDOM when a domain
       error occurred.

SEE ALSO

       acos(3), asin(3), atan(3), atan2(3), ccos(3), sin(3), sincos(3), tan(3)

COLOPHON

       This page is part of release 3.35 of the Linux man-pages project.  A  description  of  the
       project,  and information about reporting bugs, can be found at http://man7.org/linux/man-
       pages/.

                                            2010-09-11                                     COS(3)