---
title: math.nextafter() function
description: >
  `math.nextafter()` returns the next representable float value after `x` towards `y`.
menu:
  flux_v0_ref:
    name: math.nextafter
    parent: math
    identifier: math/nextafter
weight: 101
---

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`math.nextafter()` returns the next representable float value after `x` towards `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 >}})
x-value to use in the operation.



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




## Examples

- [Return the next possible float value](#return-the-next-possible-float-value)
- [Use math.nextafter in map](#use-mathnextafter-in-map)

### Return the next possible float value

```js
import "math"

math.nextafter(x: 1.23, y: 4.56)// 1.2300000000000002


```


### Use math.nextafter in map

```js
import "math"

data
    |> map(fn: (r) => ({_time: r._time, _value: math.nextafter(x: r.t1, y: r.t2)}))

```

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#### Input data

| _time                | t1    | t2    |
| -------------------- | ----- | ----- |
| 2021-01-01T00:00:00Z | -2.18 | 19.85 |
| 2021-01-01T00:00:10Z | 10.92 | 4.97  |
| 2021-01-01T00:00:20Z | 7.35  | -3.75 |
| 2021-01-01T00:00:30Z | 17.53 | 19.77 |
| 2021-01-01T00:00:40Z | 15.23 | 13.86 |
| 2021-01-01T00:00:50Z | 4.43  | 1.86  |


#### Output data

| _time                | _value              |
| -------------------- | ------------------- |
| 2021-01-01T00:00:00Z | -2.1799999999999997 |
| 2021-01-01T00:00:10Z | 10.919999999999998  |
| 2021-01-01T00:00:20Z | 7.349999999999999   |
| 2021-01-01T00:00:30Z | 17.530000000000005  |
| 2021-01-01T00:00:40Z | 15.229999999999999  |
| 2021-01-01T00:00:50Z | 4.429999999999999   |

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