> ## Documentation Index
> Fetch the complete documentation index at: https://docs.firebolt.io/llms.txt
> Use this file to discover all available pages before exploring further.

> Reference material for ATANH function

# ATANH

Calculates the inverse hyperbolic tangent (area hyperbolic tangent) of a value.

## Syntax

```sql theme={"theme":{"light":"css-variables","dark":"css-variables"}}
ATANH(<value>)
```

## Parameters

| Parameter | Description                                                                                                     | Supported input type |
| :-------- | :-------------------------------------------------------------------------------------------------------------- | :------------------- |
| `<value>` | The number that the inverse hyperbolic tangent function is applied to. Must be greater than -1 and less than 1. | `DOUBLE_PRECISION`   |

## Return Type

`ATANH` returns a value of type `DOUBLE_PRECISION`. It is defined for arguments strictly between -1 and 1; an argument outside that range raises an out-of-range error.

## Example

The inverse hyperbolic tangent of 0 is 0:

<div className="query-window">
  ```
  SELECT ATANH(0) as result;
  ```

  | result <span>double</span> |
  | :------------------------- |
  | 0                          |

  <p><span>Rows: 1</span><span>Execution time: 5.21ms</span></p>
</div>

`ATANH` undoes `TANH`, and `TANH(LN(2))` is `0.6`, so this returns `LN(2)`:

<div className="query-window">
  ```
  SELECT ATANH(0.6) as result;
  ```

  | result <span>double</span> |
  | :------------------------- |
  | 0.6931471805599453         |

  <p><span>Rows: 1</span><span>Execution time: 5.21ms</span></p>
</div>