# atanh

(PHP 4 >= 4.0.7, PHP 5)

atanh — Inverse hyperbolic tangent

### Description

float atanh ( float `$arg` )

Returns the inverse hyperbolic tangent of `arg` , i.e. the value whose hyperbolic tangent is `arg` .

> Note: This function is not implemented on Windows platforms.

### Parameters

`arg`

  The argument to process

### Return Values

Inverse hyperbolic tangent of `arg`

### See Also

- tanh()
- atan ()
- asinh()
- acosh()