# KelvinBei

KelvinBei[z]

gives the Kelvin function .

KelvinBei[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.
• KelvinBei[n,z] has a branch cut discontinuity in the complex z plane running from to .
• KelvinBei[z] is equivalent to KelvinBei[0,z].
• For certain special arguments, KelvinBei automatically evaluates to exact values.
• KelvinBei can be evaluated to arbitrary numerical precision.
• KelvinBei 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(29)

### 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 positive minimum of KelvinBei[0,x]:

For half-integer orders, KelvinBei evaluates to elementary functions:

### Visualization(3)

Plot the KelvinBei 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(6)

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 : is an even function: is an odd function:

### 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 Infinity:

Find series expansion for an arbitrary symbolic direction :

The Taylor expansion at a generic point:

### Function Identities and Simplifications(2)

Functional identity:

Recurrence relations:

## Generalizations & Extensions(1)

KelvinBei can be applied to a power series:

## Applications(2)

Solve the Kelvin differential equation:

Plot the resistance of a wire with circular cross section versus AC frequency (skin effect):

## Properties & Relations(4)

Use FullSimplify to simplify expressions involving Kelvin functions:

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

Integrate expressions involving Kelvin functions:

KelvinBei can be represented in terms of MeijerG:

Introduced in 2007
(6.0)