---
title: math.sqrt() function
description: >
  `math.sqrt()` returns the square root of `x`.
menu:
  flux_v0_ref:
    name: math.sqrt
    parent: math
    identifier: math/sqrt
weight: 101
---

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`math.sqrt()` returns the square root 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.




## Examples

- [Return the square root of a value](#return-the-square-root-of-a-value)
- [Use math.sqrt in map](#use-mathsqrt-in-map)

### Return the square root of a value

```js
import "math"

math.sqrt(x: 4.0)// 2.0


```


### Use math.sqrt in map

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

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.sqrt(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 | NaN                | t1   |
| 2021-01-01T00:00:10Z | 3.304542328371661  | t1   |
| 2021-01-01T00:00:20Z | 2.711088342345192  | t1   |
| 2021-01-01T00:00:30Z | 4.186884283091665  | t1   |
| 2021-01-01T00:00:40Z | 3.9025632602175713 | t1   |
| 2021-01-01T00:00:50Z | 2.1047565179849186 | t1   |

| _time                | _value             | *tag |
| -------------------- | ------------------ | ---- |
| 2021-01-01T00:00:00Z | 4.455333881989093  | t2   |
| 2021-01-01T00:00:10Z | 2.2293496809607953 | t2   |
| 2021-01-01T00:00:20Z | NaN                | t2   |
| 2021-01-01T00:00:30Z | 4.446346815083142  | t2   |
| 2021-01-01T00:00:40Z | 3.722902093797257  | t2   |
| 2021-01-01T00:00:50Z | 1.3638181696985856 | t2   |

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