docs-v2/content/flux/v0/stdlib/math/acosh.md

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---
title: math.acosh() function
description: >
`math.acosh()` returns the inverse hyperbolic cosine of `x`.
menu:
flux_v0_ref:
name: math.acosh
parent: math
identifier: math/acosh
weight: 101
---
<!------------------------------------------------------------------------------
IMPORTANT: This page was generated from comments in the Flux source code. Any
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To make updates to this documentation, update the function comments above the
function definition in the Flux source code:
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`math.acosh()` returns the inverse hyperbolic cosine of `x`.
##### Function type signature
```js
(x: float) => float
```
{{% caption %}}
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
{{% /caption %}}
## Parameters
### x
({{< req >}})
Value to operate on.
`x` should be greater than 1. If less than 1 the operation will return `NaN`.
## Examples
- [Return the inverse hyperbolic cosine of a value](#return-the-inverse-hyperbolic-cosine-of-a-value)
- [Use math.acosh in map](#use-mathacosh-in-map)
### Return the inverse hyperbolic cosine of a value
```js
import "math"
math.acosh(x: 1.22)
```
### Use math.acosh in map
```js
import "math"
data
|> map(fn: (r) => ({r with _value: math.acosh(x: r._value)}))
```
{{< expand-wrapper >}}
{{% expand "View example input and output" %}}
#### Input data
| _time | *tag | _value |
| -------------------- | ---- | -------------------- |
| 2021-01-01T00:00:00Z | t1 | -0.21800000000000003 |
| 2021-01-01T00:00:10Z | t1 | 1.092 |
| 2021-01-01T00:00:20Z | t1 | 0.735 |
| 2021-01-01T00:00:30Z | t1 | 1.7530000000000001 |
| 2021-01-01T00:00:40Z | t1 | 1.5230000000000001 |
| 2021-01-01T00:00:50Z | t1 | 0.443 |
| _time | *tag | _value |
| -------------------- | ---- | ------------------- |
| 2021-01-01T00:00:00Z | t2 | 1.9850000000000003 |
| 2021-01-01T00:00:10Z | t2 | 0.497 |
| 2021-01-01T00:00:20Z | t2 | -0.375 |
| 2021-01-01T00:00:30Z | t2 | 1.977 |
| 2021-01-01T00:00:40Z | t2 | 1.3860000000000001 |
| 2021-01-01T00:00:50Z | t2 | 0.18600000000000003 |
#### Output data
| _time | _value | *tag |
| -------------------- | ------------------- | ---- |
| 2021-01-01T00:00:00Z | NaN | t1 |
| 2021-01-01T00:00:10Z | 0.42572984537574377 | t1 |
| 2021-01-01T00:00:20Z | NaN | t1 |
| 2021-01-01T00:00:30Z | 1.1608966388962805 | t1 |
| 2021-01-01T00:00:40Z | 0.9827177940622978 | t1 |
| 2021-01-01T00:00:50Z | NaN | t1 |
| _time | _value | *tag |
| -------------------- | ------------------ | ---- |
| 2021-01-01T00:00:00Z | 1.308254013849232 | t2 |
| 2021-01-01T00:00:10Z | NaN | t2 |
| 2021-01-01T00:00:20Z | NaN | t2 |
| 2021-01-01T00:00:30Z | 1.3035758471451702 | t2 |
| 2021-01-01T00:00:40Z | 0.8525776257667146 | t2 |
| 2021-01-01T00:00:50Z | NaN | t2 |
{{% /expand %}}
{{< /expand-wrapper >}}