NAME

atanh, atanhf, atanhl - inverse hyperbolic tangent function

SYNOPSIS

#include <math.h>

double atanh(double x);

float atanhf(float x);

long double atanhl(long double x);

Link with -lm.

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

atanh(), atanhf(), atanhl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION

The atanh() function calculates the inverse hyperbolic tangent of x; that is the value whose hyperbolic tangent is x. If the absolute value of x is greater than 1.0, atanh() returns not-a-number (NaN) and errno is set.

ERRORS

EDOM

x is out of range.

CONFORMING TO

SVr4, POSIX.1-2001, 4.3BSD, C89. The float and long double variants are C99 requirements.

SEE ALSO

acosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)

COLOPHON

This page is part of release 2.79 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.