---
title: cov() function
description: cov() computes the covariance between two streams of tables.
url: https://docs.influxdata.com/flux/v0/stdlib/universe/cov/
estimated_tokens: 333
product: Flux
version: v0
publisher: InfluxData
canonical: https://docs.influxdata.com/flux/v0/stdlib/universe/cov/
date: '2024-04-08T16:01:02-06:00'
lastmod: '2024-04-08T16:01:02-06:00'
---

* Flux 0.7.0+

InfluxDB support

`cov()` computes the covariance between two streams of tables.

##### Function type signature

```js
(on: [string], x: A, y: B, ?pearsonr: bool) => stream[C] where C: Record
```

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

## Parameters

### x

(Required)
First input stream.

### y

(Required)
Second input stream.

### on

(Required)
List of columns to join on.

### pearsonr

Normalize results to the Pearson R coefficient. Default is `false`.

## Examples

### Return the covariance between two streams of tables

```js
import "generate"

stream1 =
    generate.from(
        count: 5,
        fn: (n) => n * n,
        start: 2021-01-01T00:00:00Z,
        stop: 2021-01-01T00:01:00Z,
    )
        |> toFloat()

stream2 =
    generate.from(
        count: 5,
        fn: (n) => n * n * n / 2,
        start: 2021-01-01T00:00:00Z,
        stop: 2021-01-01T00:01:00Z,
    )
        |> toFloat()

cov(x: stream1, y: stream2, on: ["_time"])
```

[](#view-example-output)

View example output

#### Output data

|\_value|
|-------|
| 87.75 |

#### Related

* [covariance() function](/flux/v0/stdlib/universe/covariance/)

[transformations](/flux/v0/tags/transformations/)[aggregates](/flux/v0/tags/aggregates/)
| _value |
| --- |
| _value |
| 87.75 |