---
title: math.acos() function
description: math.acos() returns the acosine of x in radians.
url: https://docs.influxdata.com/flux/v0/stdlib/math/acos/
estimated_tokens: 1389
product: Flux
version: v0
---

# math.acos() function

-   Flux 0.22.0+
-   View InfluxDB support

`math.acos()` returns the acosine of `x` in radians.

##### Function type signature

```js
(x: float) => float
```

For more information, see [Function type signatures](/flux/v0/function-type-signatures/).

## Parameters

### x

(Required) Value to operate on.

`x` should be greater than -1 and less than 1. Otherwise, the operation will return `NaN`.

## Examples

-   [Return the acosine of a value](#return-the-acosine-of-a-value)
-   [Use math.acos in map](#use-mathacos-in-map)

### Return the acosine of a value

```js
import "math"

math.acos(x: 0.22)// 1.3489818562981022

```

### Use math.acos in map

```js
import "math"

data
    |> map(fn: (r) => ({r with _value: math.acos(x: r._value)}))
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t1 | -0.021800000000000003 |
| 2021-01-01T00:00:10Z | t1 | 0.1092 |
| 2021-01-01T00:00:20Z | t1 | 0.0735 |
| 2021-01-01T00:00:30Z | t1 | 0.1753 |
| 2021-01-01T00:00:40Z | t1 | 0.15230000000000002 |
| 2021-01-01T00:00:50Z | t1 | 0.0443 |

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t2 | 0.1985 |
| 2021-01-01T00:00:10Z | t2 | 0.0497 |
| 2021-01-01T00:00:20Z | t2 | -0.0375 |
| 2021-01-01T00:00:30Z | t2 | 0.1977 |
| 2021-01-01T00:00:40Z | t2 | 0.1386 |
| 2021-01-01T00:00:50Z | t2 | 0.018600000000000002 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 1.592598053869604 | t1 |
| 2021-01-01T00:00:10Z | 1.461378125419181 | t1 |
| 2021-01-01T00:00:20Z | 1.4972299878346804 | t1 |
| 2021-01-01T00:00:30Z | 1.3945858483452276 | t1 |
| 2021-01-01T00:00:40Z | 1.417901321254124 | t1 |
| 2021-01-01T00:00:50Z | 1.5264818242659286 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 1.3709690985581462 | t2 |
| 2021-01-01T00:00:10Z | 1.5210758434398064 | t2 |
| 2021-01-01T00:00:20Z | 1.6083051214238853 | t2 |
| 2021-01-01T00:00:30Z | 1.3717852736930785 | t2 |
| 2021-01-01T00:00:40Z | 1.4317486962850596 | t2 |
| 2021-01-01T00:00:50Z | 1.5521952541518969 | t2 |