> ## Documentation Index
> Fetch the complete documentation index at: https://docs.e6data.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ACOSH

> Returns the inverse hyperbolic cosine of a number.

<div className="e6-meta"><span className="e6-eyebrow e6-eyebrow--quiet">Scalar function</span></div>

Returns NULL when an argument is NULL.

## Syntax

### Scalar

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
acosh(value)
```

## Arguments

| Name | Type | Required | Description |
| - | - | - | - |
| value | TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE or DECIMAL(p, s) | Yes | The number to evaluate. For DECIMAL(p, s), p is precision (total digits) and s is scale (digits after the decimal point). |

## Returns

* Type: DOUBLE; FLOAT when the input is evaluated as FLOAT
* Possible values: Nonnegative values for input at least 1; NaN below 1.
* NULL behavior: Returns NULL when an argument is NULL.

## Properties

| Property | Value |
| - | - |
| Deterministic | Yes |
| Supports window usage | No |
| Exact result | No |

* Approximation bound: No fixed maximum error is guaranteed.

## Usage notes

* Numeric inputs are normally converted to DOUBLE for calculation. An input evaluated as FLOAT keeps FLOAT precision.
* INTEGER and INT mean the same type; STRING means VARCHAR text. NULL can be used with a supported type. Cast NULL explicitly when its type would otherwise be unclear.
* Exact result: Floating-point computation can round the mathematical result.

## Examples

### Value and NULL input

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT acosh(CAST(1 AS DOUBLE)) AS "value", acosh(CAST(NULL AS DOUBLE)) AS null_value;
```

| value | null\_value |
| - | - |
| 0 | NULL |

### A nonzero input

The result is rounded to six decimal places for display.

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT round(acosh(CAST(2 AS DOUBLE)), 6) AS result;
```

| result |
| - |
| 1.316958 |

## Limitations

* Input below 1 produces NaN rather than NULL.
* Query tools may report DOUBLE even when the result is FLOAT. The reported type does not increase the result’s precision.


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