acosh(3) Linux Man Page - System Grab Bag

Name

acosh, acoshf, acoshl - inverse hyperbolic cosine function

Library

Math library ( libm ", " -lm )

Synopsis

#include <math.h> 
double acosh(double  x );
float acoshf(float  x );
long double acoshl(long double  x );

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

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

Description

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

Return Value

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.

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 less than 1 errno is set to EDOM .An invalid floating-point exception ( FE_INVALID ) is raised.

Attributes

For an explanation of the terms used in this section, see attributes(7). allbox; lbx lb lb T{ acosh()acoshf()acoshl()

Interface	Attribute	Value
T}	Thread safety	MT-Safe

Standards

C11, POSIX.1-2008.

History

C99, POSIX.1-2001.

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