---
title: math.lgamma() function
description: math.lgamma() returns the natural logarithm and sign (-1 or +1) of math.gamma(x:x).
url: https://docs.influxdata.com/flux/v0/stdlib/math/lgamma/
estimated_tokens: 1059
product: Flux
version: v0
publisher: InfluxData
canonical: https://docs.influxdata.com/flux/v0/stdlib/math/lgamma/
date: '2024-04-08T16:01:02-06:00'
lastmod: '2024-04-08T16:01:02-06:00'
---

* Flux 0.22.0+

InfluxDB support

`math.lgamma()` returns the natural logarithm and sign (-1 or +1) of `math.gamma(x:x)`.

##### Function type signature

```js
(x: float) => {sign: int, lgamma: float}
```

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

## Parameters

### x

(Required)
Value to operate on.

## Examples

* [Return the natural logarithm and sign of a gamma function](#return-the-natural-logarithm-and-sign-of-a-gamma-function)
* [Use math.lgamma in map](#use-mathlgamma-in-map)

### Return the natural logarithm and sign of a gamma function

```
import "math"

math.lgamma(x: 3.14)// {lgamma: 0.8261387047770286, sign: 1}

```

### Use math.lgamma in map

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

sampledata.float()
    |> map(
        fn: (r) => {
            result = math.lgamma(x: r._value)

            return {r with lgamma: result.lgamma, sign: result.sign}
        },
    )
```

[](#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|      lgamma      |sign|\*tag|
|--------------------|-------|------------------|----|-----|
|2021-01-01T00:00:00Z|\-2.18 |0.9031727084064437|\-1 | t1  |
|2021-01-01T00:00:10Z| 10.92 |14.916577673425685| 1  | t1  |
|2021-01-01T00:00:20Z| 7.35  |7.243966588004043 | 1  | t1  |
|2021-01-01T00:00:30Z| 17.53 |32.16614206633506 | 1  | t1  |
|2021-01-01T00:00:40Z| 15.23 |25.808134773211734| 1  | t1  |
|2021-01-01T00:00:50Z| 4.43  |2.3571285321490905| 1  | t1  |

|       \_time       |\_value|        lgamma        |sign|\*tag|
|--------------------|-------|----------------------|----|-----|
|2021-01-01T00:00:00Z| 19.85 |   38.8948838691485   | 1  | t2  |
|2021-01-01T00:00:10Z| 4.97  |  3.132970115904918   | 1  | t2  |
|2021-01-01T00:00:20Z|\-3.75 | \-1.3172679424463634 | 1  | t2  |
|2021-01-01T00:00:30Z| 19.77 |  38.65802514327764   | 1  | t2  |
|2021-01-01T00:00:40Z| 13.86 |  22.188483434123324  | 1  | t2  |
|2021-01-01T00:00:50Z| 1.86  |\-0.052676311706898016| 1  | t2  |
| _time | *tag | _value |
| --- | --- | --- |
| _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 |
| --- | --- | --- |
| _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 |

| _time | _value | lgamma | sign | *tag |
| --- | --- | --- | --- | --- |
| _time | _value | lgamma | sign | *tag |
| 2021-01-01T00:00:00Z | -2.18 | 0.9031727084064437 | -1 | t1 |
| 2021-01-01T00:00:10Z | 10.92 | 14.916577673425685 | 1 | t1 |
| 2021-01-01T00:00:20Z | 7.35 | 7.243966588004043 | 1 | t1 |
| 2021-01-01T00:00:30Z | 17.53 | 32.16614206633506 | 1 | t1 |
| 2021-01-01T00:00:40Z | 15.23 | 25.808134773211734 | 1 | t1 |
| 2021-01-01T00:00:50Z | 4.43 | 2.3571285321490905 | 1 | t1 |

| _time | _value | lgamma | sign | *tag |
| --- | --- | --- | --- | --- |
| _time | _value | lgamma | sign | *tag |
| 2021-01-01T00:00:00Z | 19.85 | 38.8948838691485 | 1 | t2 |
| 2021-01-01T00:00:10Z | 4.97 | 3.132970115904918 | 1 | t2 |
| 2021-01-01T00:00:20Z | -3.75 | -1.3172679424463634 | 1 | t2 |
| 2021-01-01T00:00:30Z | 19.77 | 38.65802514327764 | 1 | t2 |
| 2021-01-01T00:00:40Z | 13.86 | 22.188483434123324 | 1 | t2 |
| 2021-01-01T00:00:50Z | 1.86 | -0.052676311706898016 | 1 | t2 |