KelvinKei
✖
KelvinKei
Details

- Mathematical function, suitable for both symbolic and numerical manipulation.
- For positive real values of parameters,
. For other values,
is defined by analytic continuation.
- KelvinKei[n,z] has a branch cut discontinuity in the complex z plane running from
to
.
- KelvinKei[z] is equivalent to KelvinKei[0,z].
- For certain special arguments, KelvinKei automatically evaluates to exact values.
- KelvinKei can be evaluated to arbitrary numerical precision.
- KelvinKei automatically threads over lists.
Examples
open allclose allBasic Examples (6)Summary of the most common use cases

https://wolfram.com/xid/0cg6e5k0g-fijfgn


https://wolfram.com/xid/0cg6e5k0g-wuvub

Plot over a subset of the reals:

https://wolfram.com/xid/0cg6e5k0g-gi13sj

Plot over a subset of the complexes:

https://wolfram.com/xid/0cg6e5k0g-kiedlx

Series expansion at the origin:

https://wolfram.com/xid/0cg6e5k0g-ej957w

Series expansion at Infinity:

https://wolfram.com/xid/0cg6e5k0g-cugjvu

Series expansion at a singular point:

https://wolfram.com/xid/0cg6e5k0g-ii6s9p

Scope (34)Survey of the scope of standard use cases
Numerical Evaluation (6)

https://wolfram.com/xid/0cg6e5k0g-l274ju


https://wolfram.com/xid/0cg6e5k0g-cksbl4


https://wolfram.com/xid/0cg6e5k0g-b0wt9


https://wolfram.com/xid/0cg6e5k0g-lse7xz

The precision of the output tracks the precision of the input:

https://wolfram.com/xid/0cg6e5k0g-y7k4a


https://wolfram.com/xid/0cg6e5k0g-hfml09


https://wolfram.com/xid/0cg6e5k0g-ehgjjn

Evaluate efficiently at high precision:

https://wolfram.com/xid/0cg6e5k0g-di5gcr


https://wolfram.com/xid/0cg6e5k0g-bq2c6r

Compute average case statistical intervals using Around:

https://wolfram.com/xid/0cg6e5k0g-fp92gp

Compute the elementwise values of an array:

https://wolfram.com/xid/0cg6e5k0g-thgd2

Or compute the matrix KelvinKei function using MatrixFunction:

https://wolfram.com/xid/0cg6e5k0g-o5jpo

Specific Values (3)

https://wolfram.com/xid/0cg6e5k0g-bmqd0y


https://wolfram.com/xid/0cg6e5k0g-e41pf2

Find the first positive maximum of KelvinKei[0,x]:

https://wolfram.com/xid/0cg6e5k0g-otdu3


https://wolfram.com/xid/0cg6e5k0g-epqn1l

For some half-integer orders, KelvinKei evaluates to the same elementary functions:

https://wolfram.com/xid/0cg6e5k0g-z8bw1

Visualization (3)
Plot the KelvinKei function for integer () and half-integer (
) orders:

https://wolfram.com/xid/0cg6e5k0g-ecj8m7


https://wolfram.com/xid/0cg6e5k0g-ouu484


https://wolfram.com/xid/0cg6e5k0g-htv6ox


https://wolfram.com/xid/0cg6e5k0g-dg5uh2


https://wolfram.com/xid/0cg6e5k0g-fonszl

Function Properties (11)

https://wolfram.com/xid/0cg6e5k0g-cl7ele


https://wolfram.com/xid/0cg6e5k0g-de3irc

is defined for all real values greater than 0:

https://wolfram.com/xid/0cg6e5k0g-rrrwu

The complex domain is the whole plane except :

https://wolfram.com/xid/0cg6e5k0g-bthhjz

Approximate function range of :

https://wolfram.com/xid/0cg6e5k0g-evf2yr

Approximate function range of :

https://wolfram.com/xid/0cg6e5k0g-fphbrc


https://wolfram.com/xid/0cg6e5k0g-cpyrfv


https://wolfram.com/xid/0cg6e5k0g-gva6yl

KelvinKei is neither non-decreasing nor non-increasing:

https://wolfram.com/xid/0cg6e5k0g-2ra8g


https://wolfram.com/xid/0cg6e5k0g-b9w7up

KelvinKei is not injective:

https://wolfram.com/xid/0cg6e5k0g-g0kf


https://wolfram.com/xid/0cg6e5k0g-bb4pbr


https://wolfram.com/xid/0cg6e5k0g-b5buvp

KelvinKei is neither non-negative nor non-positive:

https://wolfram.com/xid/0cg6e5k0g-dvzykj

KelvinKei has both singularity and discontinuity for z≤0:

https://wolfram.com/xid/0cg6e5k0g-fyfbxx


https://wolfram.com/xid/0cg6e5k0g-ddyu35

KelvinKei is neither convex nor concave:

https://wolfram.com/xid/0cg6e5k0g-l0srvu

TraditionalForm formatting:

https://wolfram.com/xid/0cg6e5k0g-buf0kf

Differentiation (3)
The first derivative with respect to z:

https://wolfram.com/xid/0cg6e5k0g-krpoah

The first derivative with respect to z when n=1:

https://wolfram.com/xid/0cg6e5k0g-dk1ub4

Higher derivatives with respect to z:

https://wolfram.com/xid/0cg6e5k0g-z33jv

Plot the higher derivatives with respect to z:

https://wolfram.com/xid/0cg6e5k0g-fxwmfc

Formula for the derivative with respect to z:

https://wolfram.com/xid/0cg6e5k0g-cb5zgj

Integration (3)
Compute the indefinite integral using Integrate:

https://wolfram.com/xid/0cg6e5k0g-bponid


https://wolfram.com/xid/0cg6e5k0g-op9yly


https://wolfram.com/xid/0cg6e5k0g-b9jw7l


https://wolfram.com/xid/0cg6e5k0g-cas


https://wolfram.com/xid/0cg6e5k0g-hxu52

Series Expansions (5)
Find the Taylor expansion using Series:

https://wolfram.com/xid/0cg6e5k0g-ewr1h8

Plots of the first three approximations around :

https://wolfram.com/xid/0cg6e5k0g-binhar

The general term in the series expansion using SeriesCoefficient:

https://wolfram.com/xid/0cg6e5k0g-dznx2j

Find the series expansion at Infinity:

https://wolfram.com/xid/0cg6e5k0g-syq

Find the series expansion for an arbitrary symbolic direction :

https://wolfram.com/xid/0cg6e5k0g-t5t

The Taylor expansion at a generic point:

https://wolfram.com/xid/0cg6e5k0g-jwxla7

Generalizations & Extensions (1)Generalized and extended use cases
KelvinKei can be applied to a power series:

https://wolfram.com/xid/0cg6e5k0g-h6ba4

Applications (3)Sample problems that can be solved with this function
Solve the Kelvin differential equation:

https://wolfram.com/xid/0cg6e5k0g-ba18sk

Plot the radial density profile for alternating current within a hollow cylinder:

https://wolfram.com/xid/0cg6e5k0g-b1qyki

For some values, expressions with MeijerG are represented with KelvinKei:

https://wolfram.com/xid/0cg6e5k0g-csbpnw

Properties & Relations (4)Properties of the function, and connections to other functions
Use FullSimplify to simplify expressions involving Kelvin functions:

https://wolfram.com/xid/0cg6e5k0g-et3z14


https://wolfram.com/xid/0cg6e5k0g-bgj43d

Use FunctionExpand to expand Kelvin functions of half-integer orders:

https://wolfram.com/xid/0cg6e5k0g-nbu2rf

Integrate expressions involving Kelvin functions:

https://wolfram.com/xid/0cg6e5k0g-jzlh7p

KelvinKei can be represented in terms of MeijerG:

https://wolfram.com/xid/0cg6e5k0g-dvjg5


https://wolfram.com/xid/0cg6e5k0g-hyn7r

Wolfram Research (2007), KelvinKei, Wolfram Language function, https://reference.wolfram.com/language/ref/KelvinKei.html.
Text
Wolfram Research (2007), KelvinKei, Wolfram Language function, https://reference.wolfram.com/language/ref/KelvinKei.html.
Wolfram Research (2007), KelvinKei, Wolfram Language function, https://reference.wolfram.com/language/ref/KelvinKei.html.
CMS
Wolfram Language. 2007. "KelvinKei." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/KelvinKei.html.
Wolfram Language. 2007. "KelvinKei." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/KelvinKei.html.
APA
Wolfram Language. (2007). KelvinKei. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/KelvinKei.html
Wolfram Language. (2007). KelvinKei. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/KelvinKei.html
BibTeX
@misc{reference.wolfram_2025_kelvinkei, author="Wolfram Research", title="{KelvinKei}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/KelvinKei.html}", note=[Accessed: 29-March-2025
]}
BibLaTeX
@online{reference.wolfram_2025_kelvinkei, organization={Wolfram Research}, title={KelvinKei}, year={2007}, url={https://reference.wolfram.com/language/ref/KelvinKei.html}, note=[Accessed: 29-March-2025
]}