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

title	description	menu	weight
math.logb() function	`math.logb()` returns the binary exponent of `x`.	flux_v0_ref name parent identifier math.logb math math/logb	101

math.logb() returns the binary exponent of x.

Function type signature

(x: float) => float

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

Parameters

x

({{< req >}}) Value to operate on.

Examples

• Return the binary exponent of a value
• Use math.logb in map

Return the binary exponent of a value

import "math"

math.logb(x: 3.14)// 1

Use math.logb in map

import "sampledata"
import "math"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.logb(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	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	*tag
2021-01-01T00:00:00Z	1	t1
2021-01-01T00:00:10Z	3	t1
2021-01-01T00:00:20Z	2	t1
2021-01-01T00:00:30Z	4	t1
2021-01-01T00:00:40Z	3	t1
2021-01-01T00:00:50Z	2	t1

_time	_value	*tag
2021-01-01T00:00:00Z	4	t2
2021-01-01T00:00:10Z	2	t2
2021-01-01T00:00:20Z	1	t2
2021-01-01T00:00:30Z	4	t2
2021-01-01T00:00:40Z	3	t2
2021-01-01T00:00:50Z	0	t2

{{% /expand %}} {{< /expand-wrapper >}}