docs-v2/content/flux/v0/stdlib/math/j1.md

title	description	menu	weight
math.j1() function	`math.j1()` is a function that returns the order-one Bessel function for the first kind.	flux_v0_ref name parent identifier math.j1 math math/j1	101

math.j1() is a function that returns the order-one Bessel function for the first kind.

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 order-one Bessel function of a value
• Use math.j1 in map

Return the order-one Bessel function of a value

import "math"

math.j1(x: 1.23)// 0.5058005726280961

Use math.j1 in map

import "sampledata"
import "math"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.j1(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	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	-0.5587345375771166	t1
2021-01-01T00:00:10Z	-0.16378152627369913	t1
2021-01-01T00:00:20Z	0.096261851305172	t1
2021-01-01T00:00:30Z	-0.16615705227678823	t1
2021-01-01T00:00:40Z	0.19344160659360385	t1
2021-01-01T00:00:50Z	-0.21154289673897086	t1

_time	_value	*tag
2021-01-01T00:00:00Z	0.041529757669801666	t2
2021-01-01T00:00:10Z	-0.3240653024080138	t2
2021-01-01T00:00:20Z	-0.03322934912967974	t2
2021-01-01T00:00:30Z	0.027537686650143067	t2
2021-01-01T00:00:40Z	0.10941596518105894	t2
2021-01-01T00:00:50Z	0.5817926469097867	t2

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