# KelvinKer

KelvinKer[z]

gives the Kelvin function .

KelvinKer[n,z]

gives the Kelvin function .

# Details • Mathematical function, suitable for both symbolic and numerical manipulation.
• For positive real values of parameters, . For other values, is defined by analytic continuation.
• KelvinKer[n,z] has a branch cut discontinuity in the complex z plane running from to .
• KelvinKer[z] is equivalent to KelvinKer[0,z].
• For certain special arguments, KelvinKer automatically evaluates to exact values.
• KelvinKer can be evaluated to arbitrary numerical precision.
• KelvinKer automatically threads over lists.

# Examples

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## Basic Examples(6)

Evaluate numerically:

Plot over a subset of the reals:

Plot over a subset of the complexes:

Series expansion at the origin:

Series expansion at Infinity:

Series expansion at a singular point:

## Scope(26)

### Numerical Evaluation(4)

Evaluate numerically:

Evaluate to high precision:

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

Complex number inputs:

Evaluate efficiently at high precision:

### Specific Values(3)

Values at zero:

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

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

### Visualization(3)

Plot the KelvinKer function for integer ( ) and half-integer ( ) orders:

Plot the real part of :

Plot the imaginary part of :

Plot the real part of :

Plot the imaginary part of :

### Function Properties(5)

The real domain of :

The complex domain of : is defined for all real values greater than 0:

The complex domain is the whole plane except :

Approximate function range of :

Approximate function range of :

Functional identity:

### Differentiation(3)

The first derivative with respect to z:

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

Higher derivatives with respect to z:

Plot the higher derivatives with respect to z:

Formula for the derivative with respect to z:

### Integration(3)

Compute the indefinite integral using Integrate:

Verify the anti-derivative:

The definite integral:

More integrals:

### Series Expansions(5)

Find the Taylor expansion using Series:

Plots of the first three approximations around :

The general term in the series expansion using SeriesCoefficient:

Find the series expansion at:

Find the series expansion for an arbitrary symbolic direction :

The Taylor expansion at a generic point:

## Generalizations & Extensions(1)

KelvinKer can be applied to a power series:

## Applications(2)

Solve the Kelvin differential equation:

Plot the radial density profile for AC current in a hollow cylinder:

## Properties & Relations(3)

Use FullSimplify to simplify expressions involving Kelvin functions:

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

KelvinKer can be represented in terms of MeijerG:

Introduced in 2007
(6.0)