---
name: "atanhf"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/atanh"
---

# atanhf(3)

inverse hyperbolic tangent functions

Part of [atanh(3)](/atanh/3.md).

## NAME

**atanh**, **atanhf**, **atanhl** – inverse hyperbolic tangent functions

## LIBRARY

Math Library (libm, -lm)

## SYNOPSIS

**#include \<math.h\>**

*double*\

**atanh**(*double x*);

*float*\

**atanhf**(*float x*);

*long* *double*\

**atanhl**(*long double x*);

## DESCRIPTION

The **atanh**(), **atanhf**(), and **atanhl**() functions compute the inverse hyperbolic tangent of the real argument *x*. For a discussion of error due to roundoff, see [math(3)](/math/3.md).

## RETURN VALUES

These functions return the inverse hyperbolic tangent of *x* if successful. If the argument has absolute value 1, a divide-by-zero exception is raised and an infinity is returned. If *\|x\|* \> 1, an invalid exception is raised and an  is returned.

## SEE ALSO

[acosh(3)](/acosh/3.md), [asinh(3)](/asinh/3.md), [exp(3)](/exp/3.md), [fenv(3)](/fenv/3.md), [math(3)](/math/3.md)

## HISTORY

The **atanh**(), **atanhf**(), and **atanhl**() functions appeared in 4.3BSD, FreeBSD 2.0, and FreeBSD 10.0, respectively.