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EllipticK [m]

gives the complete elliptic integral of the first kind TemplateBox[{m}, EllipticK].

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Numerical Evaluation  
Specific Values  
Visualization  
Show More Show More
Function Properties  
Differentiation  
Integration  
Series Expansions  
Integral Transforms  
Function Representations  
Applications  
Properties & Relations  
Possible Issues  
Neat Examples  
See Also
Tech Notes
Related Guides
Related Links
History
Cite this Page

EllipticK [m]

gives the complete elliptic integral of the first kind TemplateBox[{m}, EllipticK].

Details

  • Mathematical function, suitable for both symbolic and numerical manipulation.
  • EllipticK is given in terms of the incomplete elliptic integral of the first kind by TemplateBox[{m}, EllipticK]=TemplateBox[{{pi, /, 2}, m}, EllipticF].
  • EllipticK [m] has a branch cut discontinuity in the complex m plane running from to .
  • For certain special arguments, EllipticK automatically evaluates to exact values.
  • EllipticK can be evaluated to arbitrary numerical precision.
  • EllipticK automatically threads over lists.
  • EllipticK can be used with Interval and CenteredInterval objects. »

Examples

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Basic Examples  (5)

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 :

Scope  (38)

Numerical Evaluation  (5)

Evaluate to high precision:

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

Evaluate numerically for complex arguments:

Evaluate EllipticK efficiently at high precision:

Compute worst-case guaranteed intervals using Interval and CenteredInterval objects:

Or compute average-case statistical intervals using Around :

Compute the elementwise values of an array:

Or compute the matrix EllipticK function using MatrixFunction :

Specific Values  (5)

Simple exact values are generated automatically:

Some exact values in terms of Gamma after applying FunctionExpand :

Find directional limiting values at branch cuts:

Value at infinity:

Find the root of the equation TemplateBox[{m}, EllipticK]=2:

Visualization  (2)

Plot EllipticK :

Plot the real part of TemplateBox[{z}, EllipticK]:

Plot the imaginary part of TemplateBox[{z}, EllipticK]:

Function Properties  (9)

EllipticK is defined for all real values less than 1:

EllipticK takes all real positive values:

EllipticK is not an analytic function:

Has both singularities and discontinuities:

EllipticK is not a meromorphic function:

EllipticK is nondecreasing on its domain:

EllipticK is injective:

EllipticK is not surjective:

EllipticK is non-negative on its domain:

EllipticK is convex on its domain:

Differentiation  (3)

First derivative:

Higher derivatives:

Formula for the ^(th) derivative:

Integration  (3)

Indefinite integral of EllipticK :

Definite integral over an interval lying on the branch cut:

More integrals:

Series Expansions  (3)

Taylor expansion for EllipticK :

Plot the first three approximations for EllipticK around :

Series expansions at branch points:

EllipticK can be applied to power series:

Integral Transforms  (3)

Compute the Laplace transform using LaplaceTransform :

MellinTransform :

HankelTransform :

Function Representations  (5)

Relation to other elliptic integrals:

Relation to the LegendreP :

Represent in terms of MeijerG using MeijerGReduce :

EllipticK can be represented as a DifferentialRoot :

TraditionalForm formatting:

Applications  (7)

Small-angle approximation to the period of a pendulum:

Plot the period versus the initial angle:

Vector potential due to a circular current flow, in cylindrical coordinates:

The components of the magnetic field:

Plot the magnitude of the magnetic field:

Resistance between the origin and the point in an infinite 3D lattice of unit resistors:

Energy for the Onsager solution of the Ising model:

Plot of the specific heat:

Find the critical temperature:

Calculate a singular value:

Current flow in a rectangular conducting sheet with voltage applied at a pair of opposite corners:

Plot the flow lines with bounds defined via EllipticK :

Construct lowpass elliptic filter for analog signal:

Compute filter ripple parameters and associate elliptic function parameter:

Use elliptic degree equation to find the ratio of the pass and the stop frequencies:

Compute corresponding stop frequency and elliptic parameters:

Compute ripple locations and poles and zeros of the transfer function:

Compute poles of the transfer function:

Assemble the transfer function:

Compare with the result of EllipticFilterModel :

Properties & Relations  (4)

This shows the branch cuts of the EllipticK function:

Numerically find a root of a transcendental equation:

Solve a differential equation:

EllipticK is a particular case of various mathematical functions:

Possible Issues  (3)

Machine-precision evaluation can result in numerically inaccurate answers near branch cuts:

The defining integral converges only under additional conditions:

Different argument conventions exist that result in modified results:

Neat Examples  (2)

Probability that a random walker in a 3D cubic lattice returns to the origin:

Carry out a modeling run of 1000 walks and count how many it returns to the origin:

Compare with the expected count at :

Riemann surface of TemplateBox[{m}, EllipticK]:

History

Introduced in 1988 (1.0) | Updated in 2021 (13.0) 2022 (13.1)

Wolfram Research (1988), EllipticK, Wolfram Language function, https://reference.wolfram.com/language/ref/EllipticK.html (updated 2022).

Text

Wolfram Research (1988), EllipticK, Wolfram Language function, https://reference.wolfram.com/language/ref/EllipticK.html (updated 2022).

CMS

Wolfram Language. 1988. "EllipticK." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2022. https://reference.wolfram.com/language/ref/EllipticK.html.

APA

Wolfram Language. (1988). EllipticK. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/EllipticK.html

BibTeX

@misc{reference.wolfram_2025_elliptick, author="Wolfram Research", title="{EllipticK}", year="2022", howpublished="\url{https://reference.wolfram.com/language/ref/EllipticK.html}", note=[Accessed: 24-November-2025]}

BibLaTeX

@online{reference.wolfram_2025_elliptick, organization={Wolfram Research}, title={EllipticK}, year={2022}, url={https://reference.wolfram.com/language/ref/EllipticK.html}, note=[Accessed: 24-November-2025]}

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