Hypergeometric function

Short description: Function defined by a hypergeometric series

Not to be confused with Hypergeometric distribution.

The term "hypergeometric function" sometimes refers to the generalized hypergeometric function. For other hypergeometric functions, see below.

Plot of the hypergeometric function 2F1(a,b; c; z) with a=2 and b=3 and c=4 in the complex plane from −2 − 2i to 2 + 2i with colors created with Mathematica 13.1 function ComplexPlot3D

In mathematics, the Gaussian or ordinary hypergeometric function 2F1(a, b; c; z) is a special function represented by the hypergeometric series, that includes many other special functions as specific or limiting cases. It is a solution of a second-order linear ordinary differential equation (ODE). Every second-order linear ODE with three regular singular points can be transformed into this equation.

For systematic lists of some of the many thousands of published identities involving the hypergeometric function, see the reference works by ( Erdélyi Magnus ) and ( Olde Daalhuis 2010). There is no known system for organizing all of the identities; indeed, there is no known algorithm that can generate all identities; a number of different algorithms are known that generate different series of identities. The theory of the algorithmic discovery of identities remains an active research topic.

(Note that the leading and trailing subscripts in 2F1 refer to the number of Pochhammer symbol terms in the numerator (2) and denominator (1), respectively, of the coefficients in the series definition below.)

## Contents

* 1 History
* 2 The hypergeometric series
* 3 Differentiation formulas
* 4 Special cases
* 5 The hypergeometric differential equation
* 5.1 Solutions at the singular points
* 5.2 Kummer's 24 solutions
* 5.3 Q-form
* 5.4 Schwarz triangle maps
* 5.5 Monodromy group
* 6 Integral formulas
* 6.1 Euler type
* 6.2 Barnes integral
* 6.3 John transform
* 7 Gauss's contiguous relations
* 7.1 Gauss's continued fraction
* 8 Transformation formulas
* 8.1 Fractional linear transformations
* 8.2 Quadratic transformations
* 8.3 Higher order transformations
* 9 Values at special points z
* 9.1 Special values at z = 1
* 9.2 Kummer's theorem (z = −1)
* 9.3 Values at z = 1/2
* 9.4 Other points
* 10 See also
* 11 References
* 12 External links

## History

The term "hypergeometric series" was first used by John Wallis in his 1655 book Arithmetica Infinitorum.

Hypergeometric series were studied by Leonhard Euler, but the first full systematic treatment was given by Carl Friedrich Gauss (1813).

Studies in the nineteenth century included those of Ernst Kummer (1836), and the fundamental characterisation by Bernhard Riemann (1857) of the hypergeometric function by means of the differential equation it satisfies.

Riemann showed that the second-order differential equation for 2F1(z), examined in the complex plane, could be characterised (on the Riemann sphere) by its three regular singularities.

The cases where the solutions are algebraic functions were found by Hermann Schwarz (Schwarz's list).

## The hypergeometric series

The hypergeometric function is defined for |z| < 1 by the power series

2F1(a,b;c;z)=∑n=0∞(a)n(b)n(c)nznn!=1+abcz1!+a(a+1)b(b+1)c(c+1)z22!+⋯.

It is undefined (or infinite) if c equals a non-positive integer. Here (q)n is the (rising) Pochhammer symbol,[note 1] which is defined by:

(q)n={1n=0q(q+1)⋯(q+n−1)n>0

The series terminates if either a or b is a nonpositive integer, in which case the function reduces to a polynomial:

2F1(−m,b;c;z)=∑n=0m(−1)n(mn)(b)n(c)nzn.

For complex arguments z with |z| ≥ 1 it can be analytically continued along any path in the complex plane that avoids the branch points 1 and infinity. In practice, most computer implementations of the hypergeometric function adopt a branch cut along the line z ≥ 1.

As c → −m, where m is a non-negative integer, one has 2F1(z) → ∞. Dividing by the value Γ(c) of the gamma function, we have the limit:

limc->−m2F1(a,b;c;z)Γ(c)=(a)m+1(b)m+1(m+1)!zm+12F1(a+m+1,b+m+1;m+2;z)

2F1(z) is the most common type of generalized hypergeometric series pFq.

## Differentiation formulas

Using the identity (a)n+1=a(a+1)n, it is shown that

ddz 2F1(a,b;c;z)=abc 2F1(a+1,b+1;c+1;z)

and more generally,

dndzn 2F1(a,b;c;z)=(a)n(b)n(c)n 2F1(a+n,b+n;c+n;z)

## Special cases

Many of the common mathematical functions can be expressed in terms of the hypergeometric function, or as limiting cases of it. Some typical examples are

2F1(1,1;2;−z)=ln⁡(1+z)z2F1(a,b;b;z)=(1−z)−a(b arbitrary)2F1(12,12;32;z2)=arcsin⁡(z)z2F1(13,23;32;−27x24)=3x3+27x2+423−23x3+27x2+43x3 When a = 1 and b = c, the series reduces into a plain geometric series, i.e. 2F1(1,b;b;z)=1F0(1;;z)=1+z+z2+z3+z4+⋯

hence, the name hypergeometric. This function can be considered as a generalization of the geometric series.

The confluent hypergeometric function (or Kummer's function) can be given as a limit of the hypergeometric function

M(a,c,z)=limb->∞2F1(a,b;c;b−1z)

so all functions that are essentially special cases of it, such as Bessel functions, can be expressed as limits of hypergeometric functions. These include most of the commonly used functions of mathematical physics.

Legendre functions are solutions of a second order differential equation with 3 regular singular points so can be expressed in terms of the hypergeometric function in many ways, for example

2F1(a,1−a;c;z)=Γ(c)z1−c2(1−z)c−12P−a1−c(1−2z)

Several orthogonal polynomials, including Jacobi polynomials P(α,β)n and their special cases Legendre polynomials, Chebyshev polynomials, Gegenbauer polynomials, Zernike polynomials can be written in terms of hypergeometric functions using

2F1(−n,α+1+β+n;α+1;x)=n!(α+1)nPn(α,β)(1−2x)

Other polynomials that are special cases include Krawtchouk polynomials, Meixner polynomials, Meixner–Pollaczek polynomials.

Given z∈ℂ∖{0,1}, let

τ=i2F1(12,12;1;1−z)2F1(12,12;1;z).

Then

λ(τ)=θ2(τ)4θ3(τ)4=z

is the modular lambda function, where

θ2(τ)=∑n∈ℤeπiτ(n+1/2)2,θ3(τ)=∑n∈ℤeπiτn2.

The j-invariant, a modular function, is a rational function in λ(τ).

Incomplete beta functions Bx(p, q) are related by

Bx(p,q)=xpp2F1(p,1−q;p+1;x).

The complete elliptic integrals K and E are given by[1]

K(k)=π22F1(12,12;1;k2),E(k)=π22F1(−12,12;1;k2).

## The hypergeometric differential equation

The hypergeometric function is a solution of Euler's hypergeometric differential equation

z(1−z)d2wdz2+[c−(a+b+1)z]dwdz−abw=0.

which has three regular singular points: 0,1 and ∞. The generalization of this equation to three arbitrary regular singular points is given by Riemann's differential equation. Any second order linear differential equation with three regular singular points can be converted to the hypergeometric differential equation by a change of variables.

### Solutions at the singular points

Solutions to the hypergeometric differential equation are built out of the hypergeometric series 2F1(a, b; c; z). The equation has two linearly independent solutions. At each of the three singular points 0, 1, ∞, there are usually two special solutions of the form xs times a holomorphic function of x, where s is one of the two roots of the indicial equation and x is a local variable vanishing at a regular singular point. This gives 3 × 2 = 6 special solutions, as follows.

Around the point z = 0, two independent solutions are, if c is not a non-positive integer,

2F1(a,b;c;z)

and, on condition that c is not an integer,

z1−c2F1(1+a−c,1+b−c;2−c;z)

If c is a non-positive integer 1 − m, then the first of these solutions does not exist and must be replaced by zmF(a+m,b+m;1+m;z). The second solution does not exist when c is an integer greater than 1, and is equal to the first solution, or its replacement, when c is any other integer. So when c is an integer, a more complicated expression must be used for a second solution, equal to the first solution multiplied by ln(z), plus another series in powers of z, involving the digamma function. See (Olde Daalhuis 2010) for details.

Around z = 1, if c − a − b is not an integer, one has two independent solutions

2F1(a,b;1+a+b−c;1−z)

and

(1−z)c−a−b2F1(c−a,c−b;1+c−a−b;1−z)

Around z = ∞, if a − b is not an integer, one has two independent solutions

z−a2F1(a,1+a−c;1+a−b;z−1)

and

z−b2F1(b,1+b−c;1+b−a;z−1).

Again, when the conditions of non-integrality are not met, there exist other solutions that are more complicated.

Any 3 of the above 6 solutions satisfy a linear relation as the space of solutions is 2-dimensional, giving (63) = 20 linear relations between them called connection formulas.

### Kummer's 24 solutions

A second order Fuchsian equation with n singular points has a group of symmetries acting (projectively) on its solutions, isomorphic to the Coxeter group W(Dn) of order 2n−1n!. The hypergeometric equation is the case n = 3, with group of order 24 isomorphic to the symmetric group on 4 points, as first described by Kummer. The appearance of the symmetric group is accidental and has no analogue for more than 3 singular points, and it is sometimes better to think of the group as an extension of the symmetric group on 3 points (acting as permutations of the 3 singular points) by a Klein 4-group (whose elements change the signs of the differences of the exponents at an even number of singular points). Kummer's group of 24 transformations is generated by the three transformations taking a solution F(a, b; c; z) to one of

(1−z)−aF(a,c−b;c;zz−1)F(a,b;1+a+b−c;1−z)(1−z)−bF(c−a,b;c;zz−1)

which correspond to the transpositions (12), (23), and (34) under an isomorphism with the symmetric group on 4 points 1, 2, 3, 4. (The first and third of these are actually equal to F(a, b; c; z) whereas the second is an independent solution to the differential equation.)

Applying Kummer's 24 = 6×4 transformations to the hypergeometric function gives the 6 = 2×3 solutions above corresponding to each of the 2 possible exponents at each of the 3 singular points, each of which appears 4 times because of the identities

2F1(a,b;c;z)=(1−z)c−a−b2F1(c−a,c−b;c;z)Euler transformation2F1(a,b;c;z)=(1−z)−a2F1(a,c−b;c;zz−1)Pfaff transformation2F1(a,b;c;z)=(1−z)−b2F1(c−a,b;c;zz−1)Pfaff transformation

### Q-form

The hypergeometric differential equation may be brought into the Q-form

d2udz2+Q(z)u(z)=0

by making the substitution u = wv and eliminating the first-derivative term. One finds that

Q=z2[1−(a−b)2]+z[2c(a+b−1)−4ab]+c(2−c)4z2(1−z)2

and v is given by the solution to

ddzlog⁡v(z)=−c−z(a+b+1)2z(1−z)=−c2z−1+a+b−c2(z−1)

which is

v(z)=z−c/2(1−z)(c−a−b−1)/2.

The Q-form is significant in its relation to the Schwarzian derivative (Hille 1976).

### Schwarz triangle maps

Main article: Schwarz triangle function

The Schwarz triangle maps or Schwarz s-functions are ratios of pairs of solutions.

sk(z)=ϕk(1)(z)ϕk(0)(z)

where k is one of the points 0, 1, ∞. The notation

Dk(λ,μ,ν;z)=sk(z)

is also sometimes used. Note that the connection coefficients become Möbius transformations on the triangle maps.

Note that each triangle map is regular at z ∈ {0, 1, ∞} respectively, with

s0(z)=zλ(1+𝒪(z))s1(z)=(1−z)μ(1+𝒪(1−z)) and s∞(z)=zν(1+𝒪(1z)).

In the special case of λ, μ and ν real, with 0 ≤ λ,μ,ν < 1 then the s-maps are conformal maps of the upper half-plane H to triangles on the Riemann sphere, bounded by circular arcs. This mapping is a generalization of the Schwarz–Christoffel mapping to triangles with circular arcs. The singular points 0,1 and ∞ are sent to the triangle vertices. The angles of the triangle are πλ, πμ and πν respectively.

Furthermore, in the case of λ=1/p, μ=1/q and ν=1/r for integers p, q, r, then the triangle tiles the sphere, the complex plane or the upper half plane according to whether λ + μ + ν − 1 is positive, zero or negative; and the s-maps are inverse functions of automorphic functions for the triangle group 〈p, q, r〉 = Δ(p, q, r).

### Monodromy group

The monodromy of a hypergeometric equation describes how fundamental solutions change when analytically continued around paths in the z plane that return to the same point. That is, when the path winds around a singularity of 2F1, the value of the solutions at the endpoint will differ from the starting point.

Two fundamental solutions of the hypergeometric equation are related to each other by a linear transformation; thus the monodromy is a mapping (group homomorphism):

π1(𝐂∖{0,1},z0)->GL(2,𝐂)

where π1 is the fundamental group. In other words, the monodromy is a two dimensional linear representation of the fundamental group. The monodromy group of the equation is the image of this map, i.e. the group generated by the monodromy matrices. The monodromy representation of the fundamental group can be computed explicitly in terms of the exponents at the singular points.[2] If (α, α'), (β, β') and (γ,γ') are the exponents at 0, 1 and ∞, then, taking z0 near 0, the loops around 0 and 1 have monodromy matrices

g0=(e2πiα00e2πiα′)g1=(μe2πiβ−e2πiβ′μ−1μ(e2πiβ−e2πiβ′)(μ−1)2e2πiβ′−e2πiβμe2πiβ′−e2πiβμ−1),

where

μ=sin⁡π(α+β′+γ′)sin⁡π(α′+β+γ′)sin⁡π(α′+β′+γ′)sin⁡π(α+β+γ′).

If 1 − a, c − a − b, a − b are non-integer rational numbers with denominators k, l, m then the monodromy group is finite if and only if 1/k+1/l+1/m>1, see Schwarz's list or Kovacic's algorithm.

## Integral formulas

### Euler type

If B is the beta function then

B(b,c−b)2F1(a,b;c;z)=∫01xb−1(1−x)c−b−1(1−zx)−adxℜ(c)>ℜ(b)>0,

provided that z is not a real number such that it is greater than or equal to 1. This can be proved by expanding (1 − zx)−a using the binomial theorem and then integrating term by term for z with absolute value smaller than 1, and by analytic continuation elsewhere. When z is a real number greater than or equal to 1, analytic continuation must be used, because (1 − zx) is zero at some point in the support of the integral, so the value of the integral may be ill-defined. This was given by Euler in 1748 and implies Euler's and Pfaff's hypergeometric transformations.

Other representations, corresponding to other branches, are given by taking the same integrand, but taking the path of integration to be a closed Pochhammer cycle enclosing the singularities in various orders. Such paths correspond to the monodromy action.

### Barnes integral

Barnes used the theory of residues to evaluate the Barnes integral

12πi∫−i∞i∞Γ(a+s)Γ(b+s)Γ(−s)Γ(c+s)(−z)sds

Γ(a)Γ(b)Γ(c)2F1(a,b;c;z),

where the contour is drawn to separate the poles 0, 1, 2... from the poles −a, −a − 1, ..., −b, −b − 1, ... . This is valid as long as z is not a nonnegative real number.

### John transform

The Gauss hypergeometric function can be written as a John transform (Gelfand Gindikin).

## Gauss's contiguous relations

The six functions

2F1(a±1,b;c;z),2F1(a,b±1;c;z),2F1(a,b;c±1;z)

are called contiguous to 2F1(a, b; c; z). Gauss showed that 2F1(a, b; c; z) can be written as a linear combination of any two of its contiguous functions, with rational coefficients in terms of a, b, c, and z. This gives

(62)=15

relations, given by identifying any two lines on the right hand side of

zdFdz=zabcF(a+,b+,c+)=a(F(a+)−F)=b(F(b+)−F)=(c−1)(F(c−)−F)=(c−a)F(a−)+(a−c+bz)F1−z=(c−b)F(b−)+(b−c+az)F1−z=z(c−a)(c−b)F(c+)+c(a+b−c)Fc(1−z)

where F = 2F1(a, b; c; z), F(a+) = 2F1(a \+ 1, b; c; z), and so on. Repeatedly applying these relations gives a linear relation over C(z) between any three functions of the form

2F1(a+m,b+n;c+l;z),

where m, n, and l are integers.[3] [4]

### Gauss's continued fraction

Gauss used the contiguous relations to give several ways to write a quotient of two hypergeometric functions as a continued fraction, for example:

2F1(a+1,b;c+1;z)2F1(a,b;c;z)=11+(a−c)bc(c+1)z1+(b−c−1)(a+1)(c+1)(c+2)z1+(a−c−1)(b+1)(c+2)(c+3)z1+(b−c−2)(a+2)(c+3)(c+4)z1+⋱

## Transformation formulas

Transformation formulas relate two hypergeometric functions at different values of the argument z.

### Fractional linear transformations

Euler's transformation is 2F1(a,b;c;z)=(1−z)c−a−b2F1(c−a,c−b;c;z). It follows by combining the two Pfaff transformations 2F1(a,b;c;z)=(1−z)−b2F1(b,c−a;c;zz−1)2F1(a,b;c;z)=(1−z)−a2F1(a,c−b;c;zz−1) which in turn follow from Euler's integral representation. For extension of Euler's first and second transformations, see (Rathie Paris) and (Rakha Rathie). It can also be written as linear combination 2F1(a,b;c;z)=Γ(c)Γ(c−a−b)Γ(c−a)Γ(c−b)2F1(a,b;a+b+1−c;1−z)+Γ(c)Γ(a+b−c)Γ(a)Γ(b)(1−z)c−a−b2F1(c−a,c−b;1+c−a−b;1−z).

### Quadratic transformations

If two of the numbers 1 − c, c − 1, a − b, b − a, a + b − c, c − a − b are equal or one of them is 1/2 then there is a quadratic transformation of the hypergeometric function, connecting it to a different value of z related by a quadratic equation. The first examples were given by (Kummer 1836), and a complete list was given by (Goursat 1881). A typical example is

2F1(a,b;2b;z)=(1−z)−a22F1(12a,b−12a;b+12;z24z−4)

### Higher order transformations

If 1−c, a−b, a+b−c differ by signs or two of them are 1/3 or −1/3 then there is a cubic transformation of the hypergeometric function, connecting it to a different value of z related by a cubic equation. The first examples were given by (Goursat 1881). A typical example is

2F1(32a,12(3a−1);a+12;−z23)=(1+z)1−3a2F1(a−13,a;2a;2z(3+z2)(1+z)−3)

There are also some transformations of degree 4 and 6. Transformations of other degrees only exist if a, b, and c are certain rational numbers (Vidunas 2005). For example, 2F1(14,38;78;z)(z4−60z3+134z2−60z+1)1/16=2F1(148,1748;78;−432z(z−1)2(z+1)8(z4−60z3+134z2−60z+1)3).

## Values at special points z

See (Slater 1966) for a list of summation formulas at special points, most of which also appear in (Bailey 1935). ( Gessel Stanton ) gives further evaluations at more points. (Koepf 1995) shows how most of these identities can be verified by computer algorithms.

### Special values at z = 1

Gauss's summation theorem, named for Carl Friedrich Gauss, is the identity

2F1(a,b;c;1)=Γ(c)Γ(c−a−b)Γ(c−a)Γ(c−b),ℜ(c)>ℜ(a+b)

which follows from Euler's integral formula by putting z = 1\. It includes the Vandermonde identity as a special case.

For the special case where a=−m, 2F1(−m,b;c;1)=(c−b)m(c)m

Dougall's formula generalizes this to the bilateral hypergeometric series at z = 1\.

### Kummer's theorem (z = −1)

There are many cases where hypergeometric functions can be evaluated at z = −1 by using a quadratic transformation to change z = −1 to z = 1 and then using Gauss's theorem to evaluate the result. A typical example is Kummer's theorem, named for Ernst Kummer:

2F1(a,b;1+a−b;−1)=Γ(1+a−b)Γ(1+12a)Γ(1+a)Γ(1+12a−b)

which follows from Kummer's quadratic transformations

2F1(a,b;1+a−b;z)=(1−z)−a2F1(a2,1+a2−b;1+a−b;−4z(1−z)2)=(1+z)−a2F1(a2,a+12;1+a−b;4z(1+z)2)

and Gauss's theorem by putting z = −1 in the first identity. For generalization of Kummer's summation, see ( Lavoie Grondin ).

### Values at z = 1/2

Gauss's second summation theorem is

2F1(a,b;12(1+a+b);12)=Γ(12)Γ(12(1+a+b))Γ(12(1+a))Γ(12(1+b)).

Bailey's theorem is

2F1(a,1−a;c;12)=Γ(12c)Γ(12(1+c))Γ(12(c+a))Γ(12(1+c−a)).

For generalizations of Gauss's second summation theorem and Bailey's summation theorem, see ( Lavoie Grondin ).

### Other points

There are many other formulas giving the hypergeometric function as an algebraic number at special rational values of the parameters, some of which are listed in ( Gessel Stanton ) and (Koepf 1995). Some typical examples are given by

2F1(a,−a;12;x24(x−1))=(1−x)a+(1−x)−a2,

which can be restated as

Ta(cos⁡x)=2F1(a,−a;12;12(1−cos⁡x))=cos⁡(ax)

whenever −π < x < π and T is the (generalized) Chebyshev polynomial.

## See also

* Appell series
* Basic hypergeometric series
* Bilateral hypergeometric series
* Elliptic hypergeometric series
* General hypergeometric function
* Generalized hypergeometric series
* Hypergeometric distribution
* Lauricella hypergeometric series
* Modular hypergeometric series
* Riemann's differential equation

## References

1. ↑ Morita, Tohru (1996). "Use of the Gauss contiguous relations in computing the hypergeometric functions F(n+1/2,n+1/2;m;z)". Interd. Inf. Sci. 2 (1): 63–74. doi:10.4036/iis.1996.63.
2. ↑ Ince 1944, pp. 393–393
3. ↑ Rakha, Medhat A.; Rathie, Arjun K.; Chopra, Purnima (2011). "On some new contiguous relations for the Gauss hypergeometric function with applications". Comput. Math. Appl. 61 (3): 620–629. doi:10.1016/j.camwa.2010.12.008.
4. ↑ Cho, Young Joon; Seo, Tae Young; Choi, Juensang (1999). "A note on contiguous function relations". East Asian Math. J. 15 (1): 29-38. https://koreascience.kr/article/JAKO199910736809506.page.

1. ↑ This convention is common in hypergeometric function theory, but it is the opposite convention to the one used in Falling and rising factorials.

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* Klein, Felix (1981) (in de). Vorlesungen über die hypergeometrische Funktion. Grundlehren der Mathematischen Wissenschaften. 39. Berlin, New York: Springer-Verlag. ISBN 978-3-540-10455-1. http://resolver.sub.uni-goettingen.de/purl?PPN375394591.
* Koepf, Wolfram (1995). "Algorithms for m-fold hypergeometric summation". Journal of Symbolic Computation 20 (4): 399–417. doi:10.1006/jsco.1995.1056. ISSN 0747-7171.
* Kummer, Ernst Eduard (1836). "Über die hypergeometrische Reihe 1+α⋅β1⋅γx+α(α+1)β(β+1)1⋅2⋅γ(γ+1)x2+α(α+1)(α+2)β(β+1)(β+2)1⋅2⋅3⋅γ(γ+1)(γ+2)x3+⋯" (in de). Journal für die reine und angewandte Mathematik 15: 39–83, 127–172. ISSN 0075-4102. http://resolver.sub.uni-goettingen.de/purl?GDZPPN00214056X.
* Lavoie, J. L.; Grondin, F.; Rathie, A.K. (1996). "Generalizations of Whipple's theorem on the sum of a 3F2". J. Comput. Appl. Math. 72 (2): 293–300. doi:10.1016/0377-0427(95)00279-0.
* Press, W.H.; Teukolsky, S.A.; Vetterling, W.T.; Flannery, B.P. (2007). "Section 6.13. Hypergeometric Functions". Numerical Recipes: The Art of Scientific Computing (3rd ed.). New York: Cambridge University Press. ISBN 978-0-521-88068-8. http://apps.nrbook.com/empanel/index.html#pg=318.
* Rakha, M.A.; Rathie, Arjun K. (2011). "Extensions of Euler's type-II transformation and Saalschutz's theorem". Bull. Korean Math. Soc. 48 (1): 151–156. doi:10.4134/BKMS.2011.48.1.151.
* Rathie, Arjun K.; Paris, R.B. (2007). "An extension of the Euler's-type transformation for the 3F2 series". Far East J. Math. Sci. 27 (1): 43–48.
* Riemann, Bernhard (1857). "Beiträge zur Theorie der durch die Gauss'sche Reihe F(α, β, γ, x) darstellbaren Functionen" (in de). Abhandlungen der Mathematischen Classe der Königlichen Gesellschaft der Wissenschaften zu Göttingen (Göttingen: Verlag der Dieterichschen Buchhandlung) 7: 3–22. http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=GDZPPN002018691. (a reprint of this paper can be found in "All publications of Riemann". http://www.emis.de/classics/Riemann/PFunct.pdf. )
* Slater, Lucy Joan (1960). Confluent hypergeometric functions. Cambridge, UK: Cambridge University Press. https://archive.org/details/confluenthyperge0000slat.
* Slater, Lucy Joan (1966). Generalized hypergeometric functions. Cambridge, UK: Cambridge University Press. ISBN 0-521-06483-X. (there is a 2008 paperback with ISBN 978-0-521-09061-2)
* Vidunas, Raimundas (2005). "Transformations of some Gauss hypergeometric functions". Journal of Symbolic Computation 178 (1–2): 473–487. doi:10.1016/j.cam.2004.09.053. Bibcode: 2005JCoAM.178..473V.
* Wall, H.S. (1948). Analytic Theory of Continued Fractions. D. Van Nostrand Company, Inc..
* Whittaker, E.T.; Watson, G.N. (1927). A Course of Modern Analysis. Cambridge, UK: Cambridge University Press.
* Yoshida, Masaaki (1997). Hypergeometric Functions, My Love: Modular Interpretations of Configuration Spaces. Braunschweig – Wiesbaden: Friedr. Vieweg & Sohn. ISBN 3-528-06925-2.

## External links

* Hazewinkel, Michiel, ed. (2001), "Hypergeometric function", Encyclopedia of Mathematics, Springer Science+Business Media B.V. / Kluwer Academic Publishers, ISBN 978-1-55608-010-4, https://www.encyclopediaofmath.org/index.php?title=p/h048450
* John Pearson, Computation of Hypergeometric Functions (University of Oxford, MSc Thesis)
* Marko Petkovsek, Herbert Wilf and Doron Zeilberger, The book "A = B" (freely downloadable)
* Weisstein, Eric W.. "Hypergeometric Function". http://mathworld.wolfram.com/HypergeometricFunction.html.

* v
* t
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Sequences and series

Integer
sequences|

| Basic|

* Arithmetic progression
* Geometric progression
* Harmonic progression
* Square number
* Cubic number
* Factorial
* Powers of two
* Powers of 10

|

Advanced (list)|

* Complete sequence
* Fibonacci numbers
* Figurate number
* Heptagonal number
* Hexagonal number
* Lucas number
* Pell number
* Pentagonal number
* Polygonal number
* Triangular number

Properties of sequences|

* Cauchy sequence
* Monotone sequence
* Periodic sequence

Properties of series|

* Convergent series
* Divergent series
* Conditional convergence
* Absolute convergence
* Uniform convergence
* Alternating series
* Telescoping series

Explicit series|

| Convergent|

* 1/2 − 1/4 + 1/8 − 1/16 + ⋯
* 1/2 + 1/4 + 1/8 + 1/16 + ⋯
* 1/4 + 1/16 + 1/64 + 1/256 + ⋯
* 1 + 1/2s\+ 1/3s \+ ... (Riemann zeta function)

|

Divergent|

* 1 + 1 + 1 + 1 + ⋯
* 1 + 2 + 3 + 4 + ⋯
* 1 + 2 + 4 + 8 + ⋯
* 1 − 1 + 1 − 1 + ⋯ (Grandi's series)
* Infinite arithmetic series
* 1 − 2 + 3 − 4 + ⋯
* 1 − 2 + 4 − 8 + ⋯
* 1 + 1/2 + 1/3 + 1/4 + ⋯ (harmonic series)
* 1 − 1 + 2 − 6 + 24 − 120 + ⋯ (alternating factorials)
* 1/2 + 1/3 + 1/5 + 1/7 + 1/11 + ⋯ (inverses of primes)

Kinds of series|

* Taylor series
* Power series
* Formal power series
* Laurent series
* Puiseux series
* Dirichlet series
* Trigonometric series
* Fourier series
* Generating series

Hypergeometric
series|

* Generalized hypergeometric series
* Hypergeometric function of a matrix argument
* Lauricella hypergeometric series
* Modular hypergeometric series
* Riemann's differential equation
* Theta hypergeometric series

* Book
* Category

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