HypergeometricU[a,b,z]
is the Tricomi confluent hypergeometric function ![TemplateBox[{a, b, z}, HypergeometricU] TemplateBox[{a, b, z}, HypergeometricU]](Files/HypergeometricU.en/30.png) .
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   HypergeometricU
HypergeometricU[a,b,z]
is the Tricomi confluent hypergeometric function ![TemplateBox[{a, b, z}, HypergeometricU] TemplateBox[{a, b, z}, HypergeometricU]](Files/HypergeometricU.en/1.png) .
. 
Details
 
   - Mathematical function, suitable for both symbolic and numerical manipulation.
- The function ![TemplateBox[{a, b, z}, HypergeometricU] TemplateBox[{a, b, z}, HypergeometricU]](Files/HypergeometricU.en/2.png) has the integral representation has the integral representation![TemplateBox[{a, b, z}, HypergeometricU]=1/TemplateBox[{a}, Gamma]int_0^inftye^(-zt)t^(a-1)(1+t)^(b-a-1) dt TemplateBox[{a, b, z}, HypergeometricU]=1/TemplateBox[{a}, Gamma]int_0^inftye^(-zt)t^(a-1)(1+t)^(b-a-1) dt](Files/HypergeometricU.en/3.png) . .
- HypergeometricU[a,b,z] has a branch cut discontinuity in the complex  plane running from plane running from to to . .
- For certain special arguments, HypergeometricU automatically evaluates to exact values.
- HypergeometricU can be evaluated to arbitrary numerical precision.
- HypergeometricU automatically threads over lists.
- HypergeometricU can be used with Interval and CenteredInterval objects. »
Examples
open all close allBasic Examples (5)
Plot  over a subset of the reals:
 over a subset of the reals:
Plot over a subset of the complexes:
Series expansion at the origin:
Series expansion at Infinity:
Scope (39)
Numerical Evaluation (5)
The precision of the output tracks the precision of the input:
Evaluate for complex arguments:
Evaluate HypergeometricU 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 HypergeometricU function using MatrixFunction:
Specific Values (3)
HypergeometricU automatically evaluates to simpler functions for certain parameters:
Visualization (3)
Plot the HypergeometricU function:
Plot HypergeometricU as a function of its second parameter:
Function Properties (9)
Real domain of HypergeometricU:
Complex domain of HypergeometricU:
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/13.png) is neither non-decreasing nor non-increasing on its real domain:
 is neither non-decreasing nor non-increasing on its real domain:
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/16.png) is positive on its real domain:
 is positive on its real domain:
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/17.png) has both singularity and discontinuity for z≤0:
 has both singularity and discontinuity for z≤0:
TraditionalForm formatting:
Differentiation (3)
Integration (3)
Series Expansions (3)
Series expansion for HypergeometricU:
Plot the first three approximations for ![TemplateBox[{{1, /, 2}, {sqrt(, 3, )}, x}, HypergeometricU] TemplateBox[{{1, /, 2}, {sqrt(, 3, )}, x}, HypergeometricU]](Files/HypergeometricU.en/23.png) around
 around  :
:
Expand HypergeometricU in series around infinity:
Apply HypergeometricU to a power series:
Integral Transforms (3)
Function Representations (5)
Representation through Gamma and Hypergeometric1F1:
HypergeometricU can be represented in terms of MeijerG:
HypergeometricU can be represented as a DifferentialRoot:
TraditionalForm formatting:
Applications (3)
Solve the confluent hypergeometric differential equation:
Borel summation of the divergent series for the function  gives HypergeometricU:
 gives HypergeometricU:
The same result can be obtained using the Regularization option of Sum:
Define distribution for scaled condition number of a WishartMatrixDistribution:
Sample the scaled condition number of a large matrix and check that it agrees with asymptotic closed-form distribution:
The asymptotic scaled condition number distribution has infinite mean:
Properties & Relations (4)
Use FunctionExpand to expand HypergeometricU into simpler functions:
Integrate may give results involving HypergeometricU:
HypergeometricU can be represented as a DifferentialRoot:
HypergeometricU can be represented as a DifferenceRoot:
Possible Issues (1)
The default setting of $MaxExtraPrecision can be insufficient to obtain requested precision:
 
      A larger setting for $MaxExtraPrecision may be needed:
Tech Notes
Related Guides
Related Links
History
Introduced in 1988 (1.0) | Updated in 2021 (13.0) ▪ 2022 (13.1)
Text
Wolfram Research (1988), HypergeometricU, Wolfram Language function, https://reference.wolfram.com/language/ref/HypergeometricU.html (updated 2022).
CMS
Wolfram Language. 1988. "HypergeometricU." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2022. https://reference.wolfram.com/language/ref/HypergeometricU.html.
APA
Wolfram Language. (1988). HypergeometricU. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/HypergeometricU.html
BibTeX
@misc{reference.wolfram_2025_hypergeometricu, author="Wolfram Research", title="{HypergeometricU}", year="2022", howpublished="\url{https://reference.wolfram.com/language/ref/HypergeometricU.html}", note=[Accessed: 31-October-2025]}
BibLaTeX
@online{reference.wolfram_2025_hypergeometricu, organization={Wolfram Research}, title={HypergeometricU}, year={2022}, url={https://reference.wolfram.com/language/ref/HypergeometricU.html}, note=[Accessed: 31-October-2025]}

![TemplateBox[{3, 2, x}, HypergeometricU]=1 TemplateBox[{3, 2, x}, HypergeometricU]=1](Files/HypergeometricU.en/9.png)
![TemplateBox[{{1, /, 2}, {sqrt(, 3, )}, z}, HypergeometricU] TemplateBox[{{1, /, 2}, {sqrt(, 3, )}, z}, HypergeometricU]](Files/HypergeometricU.en/10.png)
![TemplateBox[{{1, /, 2}, {sqrt(, 3, )}, z}, HypergeometricU] TemplateBox[{{1, /, 2}, {sqrt(, 3, )}, z}, HypergeometricU]](Files/HypergeometricU.en/11.png)
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/12.png)
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/14.png)
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/15.png)
![TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU] TemplateBox[{{sqrt(, 3, )}, {sqrt(, 2, )}, z}, HypergeometricU]](Files/HypergeometricU.en/18.png)



 derivative:
 derivative:![TemplateBox[{TemplateBox[{a, {a, -, b, +, 1}, c, {1, -, {c, /, z}}}, Hypergeometric2F1], c, infty}, Limit2Arg]z^(-a)=TemplateBox[{a, b, z}, HypergeometricU] TemplateBox[{TemplateBox[{a, {a, -, b, +, 1}, c, {1, -, {c, /, z}}}, Hypergeometric2F1], c, infty}, Limit2Arg]z^(-a)=TemplateBox[{a, b, z}, HypergeometricU]](Files/HypergeometricU.en/27.png)
![TemplateBox[{{1, /, 2}, {2, /, 3}, z}, HypergeometricU] TemplateBox[{{1, /, 2}, {2, /, 3}, z}, HypergeometricU]](Files/HypergeometricU.en/28.png)