docs-v2/content/flux/v0/stdlib/math/signbit.md

title	description	menu	weight
math.signbit() function	`math.signbit()` reports whether `x` is negative or negative zero.	flux_v0_ref name parent identifier math.signbit math math/signbit	101

math.signbit() reports whether x is negative or negative zero.

Function type signature

(x: float) => bool

{{% caption %}} For more information, see Function type signatures. {{% /caption %}}

Parameters

x

({{< req >}}) Value to evaluate.

Examples

• Test if a value is negative
• Use math.signbit in map

Test if a value is negative

import "math"

math.signbit(x: -1.2)// true

Use math.signbit in map

import "math"

data
    |> map(fn: (r) => ({r with _value: math.signbit(x: r._value)}))

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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

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