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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; 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
              An invalid floating-point exception (FE_INVALID) is raised.

       These functions do not set errno.

CONFORMING TO

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

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 3.24 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

                                  2009-02-04                            COS(3)