---
title: math.dim() function
description: math.dim() returns the maximum of x - y or 0.
url: https://docs.influxdata.com/flux/v0/stdlib/math/dim/
estimated_tokens: 1182
product: Flux
version: v0
---

# math.dim() function

-   Flux 0.22.0+
-   View InfluxDB support

`math.dim()` returns the maximum of `x - y` or `0`.

##### Function type signature

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

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

## Parameters

### x

(Required) x-value to use in the operation.

### y

(Required) y-value to use in the operation.

## Examples

-   [Return the maximum difference between two values](#return-the-maximum-difference-between-two-values)
-   [Use math.dim in map](#use-mathdim-in-map)

### Return the maximum difference between two values

```js
import "math"

math.dim(x: 12.2, y: 8.1)// 4.1

```

### Use math.dim in map

```js
import "math"

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

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

View example input and output

#### Input data

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

#### Output data

| _time | _value |
| --- | --- |
| 2021-01-01T00:00:00Z | 2.7 |
| 2021-01-01T01:00:00Z | 1.8000000000000003 |
| 2021-01-01T02:00:00Z | 1.6999999999999997 |
| 2021-01-01T03:00:00Z | 2 |
| 2021-01-01T04:00:00Z | 2.4000000000000004 |