atanhl(3) Linux Man Page - System Grab Bag

Name

atanh, atanhf, atanhl - inverse hyperbolic tangent function

Library

Math library ( libm ", " -lm )

Synopsis

#include <math.h> 
double atanh(double  x );
float atanhf(float  x );
long double atanhl(long double  x );

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

atanh()

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || _XOPEN_SOURCE >= 500
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

atanhf() atanhl()

    _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 tangent of x ; that is the value whose hyperbolic tangent is x.

Return Value

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

If x is a NaN, a NaN is returned.

If x is +0 (-0), +0 (-0) is returned.

If x is +1 or -1, a pole error occurs, and the functions return HUGE_VAL ,HUGE_VALF ,or HUGE_VALL ,respectively, with the mathematically correct sign.

If the absolute value of x is greater than 1, 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 less than -1 or greater than +1 errno is set to EDOM .An invalid floating-point exception ( FE_INVALID ) is raised.

Pole error: x is +1 or -1 errno is set to ERANGE (but see BUGS). A divide-by-zero floating-point exception ( FE_DIVBYZERO ) is raised.

Attributes

For an explanation of the terms used in this section, see attributes(7). allbox; lbx lb lb T{ atanh()atanhf()atanhl()

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.

Bugs

In glibc 2.9 and earlier, when a pole error occurs, errno is set to EDOM instead of the POSIX-mandated ERANGE .Since glibc 2.10, glibc does the right thing.