docs-v2/content/flux/v0/stdlib/math/j0.md

title	description	menu	weight
math.j0() function	`math.j0()` returns the order-zero Bessel function of the first kind.	flux_v0_ref name parent identifier math.j0 math math/j0	101

math.j0() returns the order-zero Bessel function of 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-zero Bessel function of a value
• Use math.j0 in map

Return the order-zero Bessel function of a value

import "math"

math.j0(x: 1.23)// 0.656070571706025

Use math.j0 in map

import "sampledata"
import "math"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.j0(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	0.12150949471274336	t1
2021-01-01T00:00:10Z	-0.1848208162077201	t1
2021-01-01T00:00:20Z	0.2837448367876356	t1
2021-01-01T00:00:30Z	-0.09816636158288365	t1
2021-01-01T00:00:40Z	-0.0602560278685108	t1
2021-01-01T00:00:50Z	-0.3360414225378073	t1

_time	_value	*tag
2021-01-01T00:00:00Z	0.17516950223786715	t2
2021-01-01T00:00:10Z	-0.18737219444686604	t2
2021-01-01T00:00:20Z	-0.4014060549361743	t2
2021-01-01T00:00:30Z	0.1779340476167977	t2
2021-01-01T00:00:40Z	0.18809934034815845	t2
2021-01-01T00:00:50Z	0.30507973268984145	t2

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