---
title: promql.linearRegression() function
description: >
  `promql.linearRegression()` implements linear regression functionality required to implement
  PromQL's [`deriv()`](https://prometheus.io/docs/prometheus/latest/querying/functions/#deriv)
  and [`predict_linear()`](https://prometheus.io/docs/prometheus/latest/querying/functions/#predict_linear) functions.
menu:
  flux_v0_ref:
    name: promql.linearRegression
    parent: internal/promql
    identifier: internal/promql/linearRegression
weight: 201
---

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`promql.linearRegression()` implements linear regression functionality required to implement
PromQL's [`deriv()`](https://prometheus.io/docs/prometheus/latest/querying/functions/#deriv)
and [`predict_linear()`](https://prometheus.io/docs/prometheus/latest/querying/functions/#predict_linear) functions.

**Important**: The `internal/promql` package is not meant for external use.

##### Function type signature

```js
(
    <-tables: stream[{A with _value: float, _time: time, _stop: time}],
    ?fromNow: float,
    ?predict: bool,
) => stream[{B with _value: float}]
```

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

## Parameters

### tables

Input data. Default is piped-forward data (`<-`).



### predict

Output should contain a prediction.



### fromNow

Time as a floating point value.