124 lines
3.0 KiB
Markdown
124 lines
3.0 KiB
Markdown
---
|
|
title: math.signbit() function
|
|
description: >
|
|
`math.signbit()` reports whether `x` is negative or negative zero.
|
|
menu:
|
|
flux_v0_ref:
|
|
name: math.signbit
|
|
parent: math
|
|
identifier: math/signbit
|
|
weight: 101
|
|
---
|
|
|
|
<!------------------------------------------------------------------------------
|
|
|
|
IMPORTANT: This page was generated from comments in the Flux source code. Any
|
|
edits made directly to this page will be overwritten the next time the
|
|
documentation is generated.
|
|
|
|
To make updates to this documentation, update the function comments above the
|
|
function definition in the Flux source code:
|
|
|
|
https://github.com/influxdata/flux/blob/master/stdlib/math/math.flux#L1961-L1961
|
|
|
|
Contributing to Flux: https://github.com/influxdata/flux#contributing
|
|
Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
|
|
|
|
------------------------------------------------------------------------------->
|
|
|
|
`math.signbit()` reports whether `x` is negative or negative zero.
|
|
|
|
|
|
|
|
##### Function type signature
|
|
|
|
```js
|
|
(x: float) => bool
|
|
```
|
|
|
|
{{% caption %}}
|
|
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
|
|
{{% /caption %}}
|
|
|
|
## Parameters
|
|
|
|
### x
|
|
({{< req >}})
|
|
Value to evaluate.
|
|
|
|
|
|
|
|
|
|
## Examples
|
|
|
|
- [Test if a value is negative](#test-if-a-value-is-negative)
|
|
- [Use math.signbit in map](#use-mathsignbit-in-map)
|
|
|
|
### Test if a value is negative
|
|
|
|
```js
|
|
import "math"
|
|
|
|
math.signbit(x: -1.2)// true
|
|
|
|
|
|
```
|
|
|
|
|
|
### Use math.signbit in map
|
|
|
|
```js
|
|
import "math"
|
|
|
|
data
|
|
|> map(fn: (r) => ({r with _value: math.signbit(x: r._value)}))
|
|
|
|
```
|
|
|
|
{{< expand-wrapper >}}
|
|
{{% expand "View example input and output" %}}
|
|
|
|
#### Input data
|
|
|
|
| _time | *tag | _value |
|
|
| -------------------- | ---- | ------- |
|
|
| 2021-01-01T00:00:00Z | t1 | -2.18 |
|
|
| 2021-01-01T00:00:10Z | t1 | -0 |
|
|
| 2021-01-01T00:00:20Z | t1 | 7.35 |
|
|
| 2021-01-01T00:00:30Z | t1 | -0 |
|
|
| 2021-01-01T00:00:40Z | t1 | -0 |
|
|
| 2021-01-01T00:00:50Z | t1 | 4.43 |
|
|
|
|
| _time | *tag | _value |
|
|
| -------------------- | ---- | ------- |
|
|
| 2021-01-01T00:00:00Z | t2 | -0 |
|
|
| 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 | -0 |
|
|
| 2021-01-01T00:00:50Z | t2 | 1.86 |
|
|
|
|
|
|
#### Output data
|
|
|
|
| _time | _value | *tag |
|
|
| -------------------- | ------- | ---- |
|
|
| 2021-01-01T00:00:00Z | true | 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 | true | t2 |
|
|
| 2021-01-01T00:00:30Z | false | t2 |
|
|
| 2021-01-01T00:00:40Z | true | t2 |
|
|
| 2021-01-01T00:00:50Z | false | t2 |
|
|
|
|
{{% /expand %}}
|
|
{{< /expand-wrapper >}}
|