---
title: math.copysign() function
description: >
  `math.copysign()` returns a value with the magnitude `x` and the sign of `y`.
menu:
  flux_v0_ref:
    name: math.copysign
    parent: math
    identifier: math/copysign
weight: 101
---

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`math.copysign()` returns a value with the magnitude `x` and the sign of `y`.



##### Function type signature

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

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

### x
({{< req >}})
Magnitude to use in the operation.



### y
({{< req >}})
Sign to use in the operation.




## Examples

- [Return the copysign of two columns](#return-the-copysign-of-two-columns)
- [Use math.copysign in map](#use-mathcopysign-in-map)

### Return the copysign of two columns

```js
import "math"

math.copysign(x: 1.0, y: 2.0)

```


### Use math.copysign in map

```js
import "math"

data
    |> map(fn: (r) => ({_time: r._time, _value: math.copysign(x: r.x, y: r.y)}))

```

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#### Input data

| _time                | x   | y    |
| -------------------- | --- | ---- |
| 2021-01-01T00:00:00Z | 1.2 | 3.9  |
| 2021-01-01T01:00:00Z | 2.4 | -4.2 |
| 2021-01-01T02:00:00Z | 3.6 | 5.3  |
| 2021-01-01T03:00:00Z | 4.8 | -6.8 |
| 2021-01-01T04:00:00Z | 5.1 | 7.5  |


#### Output data

| _time                | _value |
| -------------------- | ------ |
| 2021-01-01T00:00:00Z | 1.2    |
| 2021-01-01T01:00:00Z | -2.4   |
| 2021-01-01T02:00:00Z | 3.6    |
| 2021-01-01T03:00:00Z | -4.8   |
| 2021-01-01T04:00:00Z | 5.1    |

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