---
title: math.isInf() function
description: math.isInf() reports whether f is an infinity, according to sign.
url: https://docs.influxdata.com/flux/v0/stdlib/math/isinf/
estimated_tokens: 865
product: Flux
version: v0
publisher: InfluxData
canonical: https://docs.influxdata.com/flux/v0/stdlib/math/isinf/
date: '2024-04-08T16:01:02-06:00'
lastmod: '2024-04-08T16:01:02-06:00'
---

* Flux 0.22.0+

InfluxDB support

`math.isInf()` reports whether `f` is an infinity, according to `sign`.

If `sign > 0`, math.isInf reports whether `f` is positive infinity.
If `sign < 0`, math.isInf reports whether `f` is negative infinity.
If `sign == 0`, math.isInf reports whether `f` is either infinity.

##### Function type signature

```js
(f: float, sign: int) => bool
```

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

## Parameters

### f

(Required)
is the value used in the evaluation.

### sign

(Required)
is the sign used in the evaluation.

## Examples

* [Test if a value is an infinity value](#test-if-a-value-is-an-infinity-value)
* [Use math.isInf in map](#use-mathisinf-in-map)

### Test if a value is an infinity value

```
import "math"

math.isInf(f: 2.12, sign: 3)// false

```

### Use math.isInf in map

```js
import "math"

data
    |> map(fn: (r) => ({r with _value: math.isInf(f: r._value, sign: 1)}))
```

[](#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  | \+Inf |
|2021-01-01T00:00:20Z| t1  | 7.35  |
|2021-01-01T00:00:30Z| t1  | \+Inf |
|2021-01-01T00:00:40Z| t1  | \+Inf |
|2021-01-01T00:00:50Z| t1  | 4.43  |

|       \_time       |\*tag|\_value|
|--------------------|-----|-------|
|2021-01-01T00:00:00Z| t2  | \+Inf |
|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  | \+Inf |
|2021-01-01T00:00:50Z| t2  | 1.86  |

#### Output data

|       \_time       |\_value|\*tag|
|--------------------|-------|-----|
|2021-01-01T00:00:00Z| false | t1  |
|2021-01-01T00:00:10Z| true  | t1  |
|2021-01-01T00:00:20Z| false | t1  |
|2021-01-01T00:00:30Z| true  | t1  |
|2021-01-01T00:00:40Z| true  | t1  |
|2021-01-01T00:00:50Z| false | t1  |

|       \_time       |\_value|\*tag|
|--------------------|-------|-----|
|2021-01-01T00:00:00Z| true  | t2  |
|2021-01-01T00:00:10Z| false | t2  |
|2021-01-01T00:00:20Z| false | t2  |
|2021-01-01T00:00:30Z| false | t2  |
|2021-01-01T00:00:40Z| true  | t2  |
|2021-01-01T00:00:50Z| false | t2  |
| _time | *tag | _value |
| --- | --- | --- |
| _time | *tag | _value |
| 2021-01-01T00:00:00Z | t1 | -2.18 |
| 2021-01-01T00:00:10Z | t1 | +Inf |
| 2021-01-01T00:00:20Z | t1 | 7.35 |
| 2021-01-01T00:00:30Z | t1 | +Inf |
| 2021-01-01T00:00:40Z | t1 | +Inf |
| 2021-01-01T00:00:50Z | t1 | 4.43 |

| _time | *tag | _value |
| --- | --- | --- |
| _time | *tag | _value |
| 2021-01-01T00:00:00Z | t2 | +Inf |
| 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 | +Inf |
| 2021-01-01T00:00:50Z | t2 | 1.86 |

| _time | _value | *tag |
| --- | --- | --- |
| _time | _value | *tag |
| 2021-01-01T00:00:00Z | false | t1 |
| 2021-01-01T00:00:10Z | true | t1 |
| 2021-01-01T00:00:20Z | false | t1 |
| 2021-01-01T00:00:30Z | true | t1 |
| 2021-01-01T00:00:40Z | true | t1 |
| 2021-01-01T00:00:50Z | false | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| _time | _value | *tag |
| 2021-01-01T00:00:00Z | true | t2 |
| 2021-01-01T00:00:10Z | false | t2 |
| 2021-01-01T00:00:20Z | false | t2 |
| 2021-01-01T00:00:30Z | false | t2 |
| 2021-01-01T00:00:40Z | true | t2 |
| 2021-01-01T00:00:50Z | false | t2 |