# Futurebasic/Language/Reference/atanh

## Atanh edit

### Function edit

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### Syntax edit

result# = atanh( expr )

### Description edit

Returns the inverse hyperbolic tangent of

. This is the inverse of the *expr*`tanh`

function, so that `atanh`

`(tanh(`

equals *x*))

. *x*`atanh`

always returns a double-precision result.

### Notes edit

No special notes.