---
title: math.ilogb() function
description: math.ilogb() returns the binary exponent of x as an integer.
url: https://docs.influxdata.com/flux/v0/stdlib/math/ilogb/
estimated_tokens: 1353
product: Flux
version: v0
---

# math.ilogb() function

-   Flux 0.22.0+
-   View InfluxDB support

`math.ilogb()` returns the binary exponent of `x` as an integer.

##### Function type signature

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

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

## Parameters

### x

(Required) Value to operate on.

## Examples

-   [Return the binary exponent of a value](#return-the-binary-exponent-of-a-value)
-   [Use math.ilogb in map](#use-mathilogb-in-map)

### Return the binary exponent of a value

```js
import "math"

math.ilogb(x: 123.45)// 6

```

### Use math.ilogb in map

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

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

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

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 | t1 |
| 2021-01-01T00:00:10Z | 3 | t1 |
| 2021-01-01T00:00:20Z | 2 | t1 |
| 2021-01-01T00:00:30Z | 4 | t1 |
| 2021-01-01T00:00:40Z | 3 | t1 |
| 2021-01-01T00:00:50Z | 2 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 4 | t2 |
| 2021-01-01T00:00:10Z | 2 | t2 |
| 2021-01-01T00:00:20Z | 1 | t2 |
| 2021-01-01T00:00:30Z | 4 | t2 |
| 2021-01-01T00:00:40Z | 3 | t2 |
| 2021-01-01T00:00:50Z | 0 | t2 |