WhittakerM[k,m,z]
gives the Whittaker function 
. 
    
   WhittakerM
WhittakerM[k,m,z]
gives the Whittaker function 
. 
Details
   - Mathematical function, suitable for both symbolic and numerical manipulation.
 - WhittakerM is related to the Kummer confluent hypergeometric function by 
.  
 vanishes at 
 for 
. - For certain special arguments, WhittakerM automatically evaluates to exact values.
 - WhittakerM can be evaluated to arbitrary numerical precision.
 - WhittakerM automatically threads over lists.
 - WhittakerM[k,m,z] has a branch cut discontinuity in the complex 
 plane running from 
 to 
.  - WhittakerM can be used with Interval and CenteredInterval objects. »
 
Examples
open all close allBasic Examples (6)
Use FunctionExpand to expand in terms of hypergeometric functions:
Plot over a subset of the reals 
:
Plot over a subset of the complexes:
Series expansion at the origin:
Series expansion at Infinity:
Scope (35)
Numerical Evaluation (6)
The precision of the output tracks the precision of the input:
Evaluate efficiently at high precision:
WhittakerM can be used with Interval and CenteredInterval objects:
Compute the elementwise values of an array:
Or compute the matrix WhittakerM function using MatrixFunction:
Specific Values (7)
WhittakerM for symbolic parameters:
Find the first positive maximum of WhittakerM[5,1/2,x]:
Compute the associated WhittakerM[3,1/2,x] function:
Compute the associated WhittakerM function for half-integer parameters:
Different cases of WhittakerM give different symbolic forms:
WhittakerM threads elementwise over lists:
Visualization (3)
Plot the WhittakerM function for various orders:
Function Properties (11)
Complex domain of WhittakerM:
WhittakerM may reduce to simpler functions:
 is not an analytic function of 
 for integer values of 
:
It is analytic for other values of 
:
 is neither non-decreasing nor non-increasing:
 is neither non-negative nor non-positive on its real domain:
WhittakerM has both singularity and discontinuity in (-∞,0]:
 is neither convex nor concave on its real domain:
TraditionalForm formatting:
Differentiation (3)
Series Expansions (5)
Find the Taylor expansion using Series:
Plots of the first three approximations around 
:
General term in the series expansion using SeriesCoefficient:
Find the series expansion at Infinity:
Applications (2)
Properties & Relations (4)
Use FunctionExpand to expand WhittakerM into other functions:
Integrate expressions involving Whittaker functions:
WhittakerM can be represented as a DifferentialRoot:
WhittakerM can be represented as a DifferenceRoot:
Tech Notes
Related Guides
Related Links
History
Text
Wolfram Research (2007), WhittakerM, Wolfram Language function, https://reference.wolfram.com/language/ref/WhittakerM.html.
CMS
Wolfram Language. 2007. "WhittakerM." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/WhittakerM.html.
APA
Wolfram Language. (2007). WhittakerM. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/WhittakerM.html
BibTeX
@misc{reference.wolfram_2025_whittakerm, author="Wolfram Research", title="{WhittakerM}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/WhittakerM.html}", note=[Accessed: 04-November-2025]}
BibLaTeX
@online{reference.wolfram_2025_whittakerm, organization={Wolfram Research}, title={WhittakerM}, year={2007}, url={https://reference.wolfram.com/language/ref/WhittakerM.html}, note=[Accessed: 04-November-2025]}