---
title: math.atan() function
description: >
  `math.atan()` returns the arctangent of `x` in radians.
menu:
  flux_v0_ref:
    name: math.atan
    parent: math
    identifier: math/atan
weight: 101
---

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`math.atan()` returns the arctangent of `x` in radians.



##### 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.




## Examples

- [Return the arctangent of a value](#return-the-arctangent-of-a-value)
- [Use math.atan in map](#use-mathatan-in-map)

### Return the arctangent of a value

```js
import "math"

math.atan(x: 3.14)// 1.262480664599468


```


### Use math.atan in map

```js
import "math"
import "sampledata"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.atan(x: r._value)}))

```

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{{% expand "View example input and output" %}}

#### Input data

| _time                | *tag | _value  |
| -------------------- | ---- | ------- |
| 2021-01-01T00:00:00Z | t1   | -2.18   |
| 2021-01-01T00:00:10Z | t1   | 10.92   |
| 2021-01-01T00:00:20Z | t1   | 7.35    |
| 2021-01-01T00:00:30Z | t1   | 17.53   |
| 2021-01-01T00:00:40Z | t1   | 15.23   |
| 2021-01-01T00:00:50Z | t1   | 4.43    |

| _time                | *tag | _value  |
| -------------------- | ---- | ------- |
| 2021-01-01T00:00:00Z | t2   | 19.85   |
| 2021-01-01T00:00:10Z | t2   | 4.97    |
| 2021-01-01T00:00:20Z | t2   | -3.75   |
| 2021-01-01T00:00:30Z | t2   | 19.77   |
| 2021-01-01T00:00:40Z | t2   | 13.86   |
| 2021-01-01T00:00:50Z | t2   | 1.86    |


#### Output data

| _time                | _value             | *tag |
| -------------------- | ------------------ | ---- |
| 2021-01-01T00:00:00Z | -1.140718191739034 | t1   |
| 2021-01-01T00:00:10Z | 1.4794759377086963 | t1   |
| 2021-01-01T00:00:20Z | 1.4355721950708649 | t1   |
| 2021-01-01T00:00:30Z | 1.5138130181922385 | t1   |
| 2021-01-01T00:00:40Z | 1.5052305597197282 | t1   |
| 2021-01-01T00:00:50Z | 1.3487837105541014 | t1   |

| _time                | _value              | *tag |
| -------------------- | ------------------- | ---- |
| 2021-01-01T00:00:00Z | 1.5204610466686876  | t2   |
| 2021-01-01T00:00:10Z | 1.3722402258799695  | t2   |
| 2021-01-01T00:00:20Z | -1.3101939350475555 | t2   |
| 2021-01-01T00:00:30Z | 1.520257709140084   | t2   |
| 2021-01-01T00:00:40Z | 1.4987710606562659  | t2   |
| 2021-01-01T00:00:50Z | 1.0774963946058176  | t2   |

{{% /expand %}}
{{< /expand-wrapper >}}