KelvinBer
Details
- Mathematical function, suitable for both symbolic and numerical manipulation.
- For positive real values of parameters,
. For other values,
is defined by analytic continuation. - KelvinBer[n,z] has a branch cut discontinuity in the complex z plane running from
to
. - KelvinBer[z] is equivalent to KelvinBer[0,z].
- For certain special arguments, KelvinBer automatically evaluates to exact values.
- KelvinBer can be evaluated to arbitrary numerical precision.
- KelvinBer automatically threads over lists.
Examples
open all close allBasic Examples (6)
KelvinBer[2.5]Plot
over a subset of the reals:
ReImPlot[KelvinBer[x], {x, 0, 10}, PlotRange -> All]Plot over a subset of the complexes:
ComplexPlot3D[KelvinBer[2, z], {z, -1 - I, 1 + I}, PlotLegends -> Automatic]Series expansion at the origin:
Series[KelvinBer[x], {x, 0, 15}]Series expansion at Infinity:
Series[KelvinBer[x], {x, ∞, 2}]//FullSimplify//NormalSeries expansion at a singular point:
Series[KelvinBer[n, x], {x, -1, 2}, Assumptions -> x > 1]//FullSimplifyScope (38)
Numerical Evaluation (6)
KelvinBer[7.]KelvinBer[-1, .5]N[KelvinBer[-6, 8], 50]N[KelvinBer[-2], 50]The precision of the output tracks the precision of the input:
KelvinBer[3, 0.20444444000555555008005]N[KelvinBer[2.47, 5 - I]]N[KelvinBer[I + 1.47, 5]]Evaluate efficiently at high precision:
KelvinBer[7, 5`100]//TimingKelvinBer[7, 5`100000];//TimingCompute average-case statistical intervals using Around:
KelvinBer[Around[1 / 2, 0.1]]Compute the elementwise values of an array:
KelvinBer[{{0, 1.2I}, {1.2I, 0}}]Or compute the matrix KelvinBer function using MatrixFunction:
MatrixFunction[KelvinBer, {{0, 1.2I}, {1.2, 0}}]Specific Values (3)
KelvinBer[0]KelvinBer[1, 0]Find the first positive minimum of KelvinBer[0,x]:
xmin = x /. FindRoot[D[KelvinBer[0, x], x] == 0, {x, 5}]Plot[KelvinBer[0, x], {x, -1, 10}, Epilog -> Style[Point[{xmin, KelvinBer[0, xmin]}], PointSize[Large], Red]]For half-integer orders, KelvinBer evaluates to elementary functions:
Table[KelvinBer[n, x Sqrt[2]], {n, {-1 / 2, 1 / 2}}]//FunctionExpandVisualization (3)
Plot the KelvinBer function for integer (
) and half-integer (
) orders:
ReImPlot[{KelvinBer[0, x], KelvinBer[1, x], KelvinBer[-1 / 2, x]}, {x, 0, 14}, PlotRange -> {-1000, 400}]ComplexContourPlot[Re[KelvinBer[0, z]], {z, -3 - 6I, 3 + 6I}, IconizedObject[«PlotOptions»]]ComplexContourPlot[Im[KelvinBer[0, z]], {z, -3 - 6I, 3 + 6I}, IconizedObject[«PlotOptions»]]ComplexContourPlot[Re[KelvinBer[-1 / 4, z]], {z, -3 - 6I, 3 + 6I}, IconizedObject[«PlotOptions»]]ComplexContourPlot[Im[KelvinBer[-1 / 4, z]], {z, -3 - 6I, 3 + 6I}, IconizedObject[«PLotOptions»]]Function Properties (13)
FunctionDomain[KelvinBer[0, x], x]FunctionDomain[KelvinBer[0, z], z, Complexes]
is defined for all real values greater than 0:
FunctionDomain[KelvinBer[-1 / 2, x], x]The complex domain is the whole plane except
:
FunctionDomain[KelvinBer[-1 / 2, z], z, Complexes]FunctionRange[KelvinBer[0, x], x, y]//QuietApproximate function range of
:
FunctionRange[KelvinBer[1, x], x, y]//QuietKelvinBer[0, -x]KelvinBer[1, -x]KelvinBer threads elementwise over lists:
KelvinBer[{1, 2, 3}, 1.0]FunctionAnalytic[KelvinBer[0, z], z]KelvinBer is neither non-decreasing nor non-increasing:
Table[FunctionMonotonicity[KelvinBer[n, x], x, PositiveReals], {n, 4}]Table[FunctionMonotonicity[KelvinBer[1 / n, x], x, PositiveReals], {n, 4}]KelvinBer is not injective:
Table[FunctionInjective[KelvinBer[n, x], x], {n, 4}]Table[FunctionInjective[KelvinBer[1 / n, x], x], {n, 4}]Plot[{KelvinBer[1, x], KelvinBer[2, x], KelvinBer[1 / 3, x], -3, 1}, {x, 0, 7}]KelvinBer is neither non-negative nor non-positive:
Table[FunctionSign[KelvinBer[n, x], x, PositiveReals], {n, 4}]
has singularities or discontinuities in the non-positive reals when
is not an integer:
FunctionSingularities[KelvinBer[n, x], x]FunctionDiscontinuities[KelvinBer[n, x], x]KelvinBer is neither convex nor concave:
Table[FunctionConvexity[{KelvinBer[a, x], x > 0}, x], {a, 5}]TraditionalForm formatting:
KelvinBer[n, x]//TraditionalFormDifferentiation (3)
The first derivative with respect to
:
D[KelvinBer[x], x]The first derivative with respect to
when
:
D[KelvinBer[1, x], x]Higher derivatives with respect to
:
Table[D[KelvinBer[x], {x, k}], {k, 1, 5}]//SimplifyPlot the higher derivatives with respect to
:
Plot[%, {x, -20, 20}, PlotLegends -> {"First Derivative", "Second Derivative", "Third Derivative", "Fourth Derivative", "Fifth Derivative"}]Formula for the ![]()
derivative with respect to
:
D[KelvinBer[x], {x, k}]// FullSimplifyIntegration (3)
Compute the indefinite integral using Integrate:
Integrate[KelvinBer[x], x]// FullSimplifyFullSimplify[D[%, x]]// FullSimplifyIntegrate[KelvinBer[x], {x, 0, 3}]Integrate[x KelvinBer[x]^2, x]// FullSimplifyIntegrate[x^2 KelvinBer[x], {x, 0, 10}]// FullSimplifySeries Expansions (5)
Find the Taylor expansion using Series:
Series[KelvinBer[n, x], {x, 0, 3}]Plots of the first three approximations around
:
terms = Normal@Table[Series[KelvinBer[x], {x, 2, m}], {m, 1, 5, 2}];
Plot[{KelvinBer[x], terms}, {x, 0, 10}]The general term in the series expansion using SeriesCoefficient:
SeriesCoefficient[KelvinBer[x], {x, 1, m}]// FullSimplifyFind the series expansion at Infinity:
Series[KelvinBer[x], {x, Infinity, 1}]// Normal//FullSimplifyFind the series expansion for an arbitrary symbolic direction
:
Series[KelvinBer[x], {x, DirectedInfinity[z], 1}, Assumptions -> x > 0 && z > 0]//Normal//FullSimplify//QuietThe Taylor expansion at a generic point:
Series[KelvinBer[x], {x, x0, 2}]// FullSimplifyFunction Identities and Simplifications (2)
KelvinBer[n, x] == -(1/2 Sqrt[2] n)x (KelvinBei[-1 + n, x] + KelvinBei[1 + n, x] + KelvinBer[-1 + n, x] + KelvinBer[1 + n, x])//FullSimplifyKelvinBer[n, x] == (Sqrt[2] (1 + n) (KelvinBei[1 + n, x] - KelvinBer[1 + n, x])/x) - KelvinBer[2 + n, x]//FullSimplifyGeneralizations & Extensions (1)
KelvinBer can be applied to a power series:
KelvinBer[0, Sin[x] + O[x] ^ 10]Applications (3)
Solve the Kelvin differential equation:
DSolve[x^4 Derivative[4][f][x] + 2 x^3 Derivative[3][f][x] - (1 + 2 n^2) (-x Derivative[1][f][x] + x^2 Derivative[2][f][x]) + ((n^2 - 4) n^2 + x^4) f[x] == 0, f[x], x]Plot the resistance of a wire with circular cross section versus AC frequency (skin effect):
Plot[ω / 2 ( KelvinBer[ω]KelvinBei'[ω] - KelvinBei[ω]KelvinBer'[ω]) / (KelvinBer'[ω] ^ 2 + KelvinBei'[ω] ^ 2), {ω, 0, 4}]This specific MeijerG is simplified to KelvinBei and KelvinBer functions:
(Sqrt[π]/2)(MeijerG[{{}, {}}, {{0}, {0, 0, (1/2)}}, ((-1)^1 / 4 x/2 Sqrt[2]), 1 / 4] + Sqrt[2] MeijerG[{{(1/2)}, {(1/4)}}, {{0}, {0, 0, (1/4)}}, (-1)^1 / 4 x, 1 / 2])//FullSimplifyProperties & Relations (5)
The one‐argument form evaluates to the two-argument form:
KelvinBer[x]Use FullSimplify to simplify expressions involving Kelvin functions:
D[x KelvinBer[1, x], x]FullSimplify[%]Use FunctionExpand to expand Kelvin functions of half-integer orders:
FunctionExpand[KelvinBer[(1/2), x]]Integrate expressions involving Kelvin functions:
Integrate[x (KelvinBer[x]^2 + KelvinBei[x]^2), x]KelvinBer can be represented in terms of MeijerG:
MeijerGReduce[KelvinBer[n, x], x]Activate[%]//FullSimplifyTech Notes
Related Guides
Related Links
History
Text
Wolfram Research (2007), KelvinBer, Wolfram Language function, https://reference.wolfram.com/language/ref/KelvinBer.html.
CMS
Wolfram Language. 2007. "KelvinBer." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/KelvinBer.html.
APA
Wolfram Language. (2007). KelvinBer. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/KelvinBer.html
BibTeX
@misc{reference.wolfram_2026_kelvinber, author="Wolfram Research", title="{KelvinBer}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/KelvinBer.html}", note=[Accessed: 13-June-2026]}
BibLaTeX
@online{reference.wolfram_2026_kelvinber, organization={Wolfram Research}, title={KelvinBer}, year={2007}, url={https://reference.wolfram.com/language/ref/KelvinBer.html}, note=[Accessed: 13-June-2026]}