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

title	description	menu	weight
math.jn() function	`math.jn()` returns the order-n Bessel function of the first kind.	flux_v0_ref name parent identifier math.jn math math/jn	101

math.jn() returns the order-n Bessel function of the first kind.

Function type signature

(n: int, x: float) => float

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

Parameters

n

({{< req >}}) Order number.

x

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

Examples

• Return the order-n Bessel function of a value
• Use math.jn in map

Return the order-n Bessel function of a value

import "math"

math.jn(n: 2, x: 1.23)// 0.16636938378681407

Use math.jn in map

import "sampledata"
import "math"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.jn(n: 4, 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	0.046148335742456664	t1
2021-01-01T00:00:10Z	-0.03367382202216673	t1
2021-01-01T00:00:20Z	0.06455053599079605	t1
2021-01-01T00:00:30Z	-0.016152633110842446	t1
2021-01-01T00:00:40Z	-0.15300380439231542	t1
2021-01-01T00:00:50Z	0.3401384178914538	t1

_time	_value	*tag
2021-01-01T00:00:00Z	0.14801732445932958	t2
2021-01-01T00:00:10Z	0.3896093468299793	t2
2021-01-01T00:00:20Z	0.24301709268606153	t2
2021-01-01T00:00:30Z	0.15603599253486927	t2
2021-01-01T00:00:40Z	0.10341672446511223	t2
2021-01-01T00:00:50Z	0.026150267042506597	t2

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