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math.j0() function

content/flux/v0/stdlib/math/j0.md

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<!------------------------------------------------------------------------------ IMPORTANT: This page was generated from comments in the Flux source code. Any edits made directly to this page will be overwritten the next time the documentation is generated. To make updates to this documentation, update the function comments above the function definition in the Flux source code: https://github.com/influxdata/flux/blob/master/stdlib/math/math.flux#L1192-L1192 Contributing to Flux: https://github.com/influxdata/flux#contributing Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md ------------------------------------------------------------------------------->

math.j0() returns the order-zero Bessel function of the first kind.

Function type signature
js
(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

js
import "math"

math.j0(x: 1.23)// 0.656070571706025

Use math.j0 in map

js
import "sampledata"
import "math"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.j0(x: r._value)}))

{{< expand-wrapper >}} {{% expand "View example input and output" %}}

Input data

_time*tag_value
2021-01-01T00:00:00Zt1-2.18
2021-01-01T00:00:10Zt110.92
2021-01-01T00:00:20Zt17.35
2021-01-01T00:00:30Zt117.53
2021-01-01T00:00:40Zt115.23
2021-01-01T00:00:50Zt14.43
_time*tag_value
2021-01-01T00:00:00Zt219.85
2021-01-01T00:00:10Zt24.97
2021-01-01T00:00:20Zt2-3.75
2021-01-01T00:00:30Zt219.77
2021-01-01T00:00:40Zt213.86
2021-01-01T00:00:50Zt21.86

Output data

_time_value*tag
2021-01-01T00:00:00Z0.12150949471274336t1
2021-01-01T00:00:10Z-0.1848208162077201t1
2021-01-01T00:00:20Z0.2837448367876356t1
2021-01-01T00:00:30Z-0.09816636158288365t1
2021-01-01T00:00:40Z-0.0602560278685108t1
2021-01-01T00:00:50Z-0.3360414225378073t1
_time_value*tag
2021-01-01T00:00:00Z0.17516950223786715t2
2021-01-01T00:00:10Z-0.18737219444686604t2
2021-01-01T00:00:20Z-0.4014060549361743t2
2021-01-01T00:00:30Z0.1779340476167977t2
2021-01-01T00:00:40Z0.18809934034815845t2
2021-01-01T00:00:50Z0.30507973268984145t2

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