Beta

Beta[a,b]

gives the Euler beta function TemplateBox[{a, b}, Beta].

Beta[z,a,b]

gives the incomplete beta function TemplateBox[{z, a, b}, Beta3].

Details

  • Beta is a mathematical function, suitable for both symbolic and numerical manipulation.
  • TemplateBox[{a, b}, Beta]=TemplateBox[{a}, Gamma]TemplateBox[{b}, Gamma]/TemplateBox[{{a, +, b}}, Gamma]=int_0^1t^(a-1)(1-t)^(b-1)dt.
  • TemplateBox[{z, a, b}, Beta3]=int_0^zt^(a-1)(1-t)^(b-1)dt.
  • Beta[z,a,b] has a branch cut discontinuity in the complex plane running from to .
  • Beta[z0,z1,a,b] gives the generalized incomplete beta function .
  • Note that the arguments in the incomplete form of Beta are arranged differently from those in the incomplete form of Gamma.
  • For certain special arguments, Beta automatically evaluates to exact values.
  • Beta can be evaluated to arbitrary numerical precision.
  • Beta automatically threads over lists.
  • In TraditionalForm, Beta is output using \[CapitalBeta].
  • Beta can be used with Interval and CenteredInterval objects. »

Examples

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Basic Examples  (6)

Exact values:

Evaluate numerically:

Plot TemplateBox[{{1, /, 2}, b}, Beta] over a subset of the reals:

Plot the incomplete beta function over a subset of the reals:

Plot over a subset of the complexes:

Series expansion at the origin:

Series expansion at Infinity:

Scope  (42)

Numerical Evaluation  (8)

Evaluate numerically:

Evaluate symbolically in special cases:

Evaluate to high precision:

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

Evaluate for large arguments:

Evaluate for complex arguments:

Evaluate Beta 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 Beta function using MatrixFunction:

Specific Values  (4)

Values at infinity:

Find a zero of TemplateBox[{x, {-, {1, /, 2}}}, Beta]=0:

Evaluate the incomplete beta function symbolically at integer and halfinteger orders:

Evaluate the generalized incomplete beta symbolically:

Visualization  (2)

Plot TemplateBox[{{1, /, 2}, b}, Beta]:

Contour plot of TemplateBox[{a, b}, Beta]:

Function Properties  (11)

Real domain of the complete Euler beta function:

Complex domain:

Permutation symmetry:

Euler beta function has the mirror property TemplateBox[{TemplateBox[{a}, Conjugate, SyntaxForm -> SuperscriptBox], TemplateBox[{b}, Conjugate, SyntaxForm -> SuperscriptBox]}, Beta]=TemplateBox[{TemplateBox[{a, b}, Beta]}, Conjugate]:

The complete beta function is not an analytic function:

However, it is meromorphic:

Its singularities and discontinuities are restricted to the non-positive integers:

The incomplete beta function TemplateBox[{x, a, 1}, Beta3] is an analytic function of for positive integer :

Thus, any such function will have no singularities or discontinuities:

For other values of , TemplateBox[{x, a, 1}, Beta3] is neither analytic nor meromorphic:

TemplateBox[{x, 1, 2}, Beta3] is neither non-increasing nor non-decreasing:

TemplateBox[{x, a, 1}, Beta3] is injective for positive odd but not positive even :

TemplateBox[{x, a, 1}, Beta3] is surjective for positive odd but not positive even :

TemplateBox[{x, a, 1}, Beta3] is non-negative for positive even but indefinite for odd :

TemplateBox[{x, a, 1}, Beta3] is convex for positive even :

TraditionalForm formatting:

Differentiation  (2)

First derivative of the beta function:

Higher derivatives of the beta function:

Plot higher derivatives for :

Series Expansions  (5)

The beta function series expansion at poles:

The first term in the beta function series expansion around :

Asymptotic expansion of the beta function:

Incomplete beta function series expansion at any point:

Beta can be applied to power series:

Function Identities and Simplifications  (4)

Generalized incomplete beta function is related to incomplete beta function:

Use FullSimplify to simplify beta functions:

Recurrence relationships:

Product relation:

Function Representations  (6)

Primary definition in terms of Gamma function:

Reduce the generalized incomplete beta function to incomplete beta functions:

Integral representation of the Euler beta function:

Integral representation of the incomplete beta function:

Beta can be represented in terms of MeijerG:

Beta can be represented as a DifferentialRoot:

Generalizations & Extensions  (6)

Euler Beta Function  (2)

Evaluate symbolically in special cases:

Beta threads elementwise over lists:

Incomplete Beta Function  (2)

Evaluate symbolically at integer and halfinteger orders:

Series expansion at any point:

Generalized Incomplete Beta Function  (2)

Generalized incomplete beta function is related to incomplete beta function:

Evaluate symbolically:

Applications  (5)

Plot the beta function for real positive values:

Plot of the absolute value of Beta in the complex plane:

Distribution of the average distance s of all pairs of points in a ddimensional hypersphere:

Lowdimensional distributions can be expressed in elementary functions:

Plot distributions:

The PDF for the beta distribution for random variable :

Plot the PDF for various parameters:

Calculate the mean:

The probability that more than (capacity) simultaneous service requests are made can be represented in terms of Gamma and Beta functions:

Properties & Relations  (7)

Express the Euler beta function as a ratio of Euler gamma functions:

Reduce the generalized incomplete beta function to incomplete beta functions:

Use FullSimplify to simplify beta functions:

Numerically find a root of a transcendental equation:

Sum expressions involving Beta:

Generating function:

Obtain as special cases of hypergeometric functions:

Beta can be represented as a DifferenceRoot:

Possible Issues  (4)

Large arguments can give results too small to be computed explicitly:

Machinenumber inputs can give highprecision results:

Algorithmically generated results often use gamma and hypergeometric rather than beta functions:

The differential equation is satisfied by a sum of incomplete beta functions:

Beta functions are typically not generated by FullSimplify:

Neat Examples  (2)

Nest Beta over the complex plane:

Define the beta matrix, whose entries are reciprocals of beta functions:

The determinant of the beta matrix is :

The beta matrix is symmetric positive definite, and its Cholesky decomposition has entries of the form sqrt(i) TemplateBox[{j, i}, Binomial]:

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

Text

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

CMS

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

APA

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

BibTeX

@misc{reference.wolfram_2024_beta, author="Wolfram Research", title="{Beta}", year="2022", howpublished="\url{https://reference.wolfram.com/language/ref/Beta.html}", note=[Accessed: 04-October-2024 ]}

BibLaTeX

@online{reference.wolfram_2024_beta, organization={Wolfram Research}, title={Beta}, year={2022}, url={https://reference.wolfram.com/language/ref/Beta.html}, note=[Accessed: 04-October-2024 ]}