acosh - Man Page

Math library (libm, -lm)

#include <math.h>

double acosh(double x);
float acoshf(float x);
long double acoshl(long double x);

acosh():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || _XOPEN_SOURCE >= 500
        || /* Since 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

These functions calculate the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x.

On success, these functions return the inverse hyperbolic cosine of x.

If x is a NaN, a NaN is returned.

If x is +1, +0 is returned.

If x is positive infinity, positive infinity is returned.

If x is less than 1, a domain error occurs, and the functions return a NaN.

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 less than 1

errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.

For an explanation of the terms used in this section, see attributes(7).

C11, POSIX.1-2008.

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD.

asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)

asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3).

The man pages acoshf(3) and acoshl(3) are aliases of acosh(3).