cos(3) Library Functions Manual cos(3) cos, cosf, cosl - (libm -lm) #include double cos(double x); float cosf(float x); long double cosl(long double x); glibc ( feature_test_macros(7)): cosf(), cosl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE x x . x. x (NaN) NaN. x NaN ( ). math_error(7) . : : x errno EDOM ( BUGS). (FE_INVALID). attributes(7). +------------+------------------------------------+--------------------+ || | | +------------+------------------------------------+--------------------+ |cos(), | | MT-Safe | |cosf(), | | | |cosl() | | | +------------+------------------------------------+--------------------+ C11, POSIX.1-2008. C89, POSIX.1-2001. double SVr4 4.3BSD. glibc 2.10 glibc errno EDOM . acos(3), asin(3), atan(3), atan2(3), ccos(3), sin(3), sincos(3), tan(3) 3 . . : . 6.18 8 2026 cos(3)