acosh(3) Library Functions Manual acosh(3) acosh, acoshf, acoshl - (libm -lm) #include double acosh(double x); float acoshf(float x); long double acoshl(long double x); glibc ( feature_test_macros(7)): acosh(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE acoshf(), acoshl(): _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 +1 +0. x . x 1 NaN. math_error(7) . : : x 1 errno EDOM. (FE_INVALID). attributes(7). +------------+------------------------------------+--------------------+ || | | +------------+------------------------------------+--------------------+ |acosh(), | | MT-Safe | |acoshf(), | | | |acoshl() | | | +------------+------------------------------------+--------------------+ C11, POSIX.1-2008. C99 POSIX.1-2001. double SVr4 4.3BSD. asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3) 3 . . : . 6.18 8 2026 acosh(3)