오일러-가우스 초기하함수2F1

수학노트
둘러보기로 가기 검색하러 가기

개요

  • 초기하급수\[\,_2F_1(a,b;c;z)=\sum_{n=0}^{\infty} \frac{(a)_n(b)_n}{(c)_nn!}z^n, |z|<1\]

여기서 \((a)_n=a(a+1)(a+2)...(a+n-1)\)에 대해서는 포흐하머 (Pochhammer) 기호 항목 참조

  • 적분표현\[\,_2F_1(a,b;c;z)=\frac{\Gamma(c)}{\Gamma(c-a)\Gamma(a)}\int_0^1t^{a-1}(1-t)^{c-a-1}(1-zt)^{-b}\,dt\]
  • 초기하급수의 해석적확장을 통해 얻어진 함수를 초기하함수라 함
  • 오일러, 가우스, 쿰머, 리만,슈워츠 등의 연구



초기하급수로 표현되는 함수의 예



초기하 미분방정식

  • \(w(z)=\,_2F_1(a,b;c;z)\) 는 다음 피카드-Fuchs 형태의 미분방정식의 해가 된다

\[z(1-z)\frac{d^2w}{dz^2}+(c-(a+b+1)z)\frac{dw}{dz}-abw = 0\]




오일러의 변환 공식

\(_2F_1 (a,b;c;z) = (1-z)^{-a} {}_2F_1 (a, c-b;c ; \frac{z}{z-1})\)

\(_2F_1 (a,b;c;z) = (1-z)^{-b}{}_2F_1(c-a,b;c;\frac{z}{z-1})\)

\(_2F_1 (a,b;c;z) = (1-z)^{c-a-b}{}_2F_1 (c-a, c-b;c ; z)\)


증명

다음 적분표현을 활용

\(\,_2F_1(a,b;c;z)=\frac{\Gamma(c)}{\Gamma(c-a)\Gamma(a)}\int_0^1t^{a-1}(1-t)^{c-a-1}(1-zt)^{-b}\,dt\)

위의 우변에서 \(t\to 1-t\), \(t\to \frac{t}{1-z-tz}\), \(t\to \frac{1-t}{1-tz}\)의 변환을 이용하면 항등식이 얻어진다. ■



contiguous 관계



타원적분과 초기하급수



모듈라 함수와의 관계



슈워츠 s-함수



special values

  • Chu-Vandermonde 공식\[\,_2F_1(-n,b;c;1)=\dfrac{(c-b)_{n}}{(c)_{n}}\] 아래 가우스 공식에서 \(a=-n\)인 경우에 얻어진다
  • 가우스 공식\[\,_2F_1(a,b;c;1)=\dfrac{\Gamma(c)\,\Gamma(c-a-b)}{\Gamma(c-a)\Gamma(c-b)}\]
  • 위의 두 식에 대해서는 초기하 급수의 합공식
  • 렘니스케이트(lemniscate) 곡선과 타원적분\[\frac{\pi}{2}\,_2F_1(\frac{1}{2},\frac{1}{2};1;\frac{1}{2})=K(\frac{1}{\sqrt{2}})=\frac{1}{4}B(1/4,1/4)=\frac{\Gamma(\frac{1}{4})^2}{4\sqrt{\pi}}=1.8540746773\cdots\]
  • http://mathworld.wolfram.com/HypergeometricFunction.html\[_2F_1(\frac{1}{3},\frac{2}{3};\frac{5}{6};\frac{27}{32})=\frac{8}{5}\]\[_2F_1(\frac{1}{4},\frac{1}{2};\frac{3}{4};\frac{80}{81})=\frac{9}{5}\]\[_2F_1(\frac{1}{8},\frac{3}{8};\frac{1}{2};\frac{2400}{2401})=\frac{2}{3}\sqrt{7}\]\[_2F_1(\frac{1}{6},\frac{1}{3};\frac{1}{2};\frac{25}{27})=\frac{3}{4}\sqrt{3}\]\[_2F_1(\frac{1}{6},\frac{1}{2};\frac{2}{3};\frac{125}{128})=\frac{4}{3}\sqrt[6]2\]\[_2F_1(\frac{1}{12},\frac{5}{12};\frac{1}{2};\frac{1323}{1331})=\frac{3}{4}\sqrt[4]{11}\]\[_2F_1(\frac{1}{12},\frac{5}{12};\frac{1}{2};\frac{121}{125})=\frac{\sqrt[6]{2}\sqrt[4]{15}}{4\sqrt{\pi}}\frac{\Gamma(\frac{1}{3})^3}{\Gamma(\frac{1}{4})^2}(1+\sqrt{3})\]



역사



관련된 항목들


매스매티카 파일 및 계산 리소스



사전 형태의 자료



리뷰논문, 에세이, 강의노트



관련논문

말뭉치

  1. This paper introduces the hypergeo package of R routines, for numerical calculation of hypergeometric functions.[1]
  2. The package is focussed on ecient and accurate evaluation of the hypergeometric function over the whole of the complex plane within the constraints of xed-precision arithmetic.[1]
  3. 2 Numerical evaluation of the Gauss hypergeometric function with the hypergeo package when dened.[1]
  4. Writing a, b, c for the two upper and one lower argument respectively, the resulting function 2F1 (a, b; c; z) is known as the hypergeometric function.[1]
  5. For systematic lists of some of the many thousands of published identities involving the hypergeometric function, see the reference works by Erdélyi et al.[2]
  6. Elliptic modular functions can sometimes be expressed as the inverse functions of ratios of hypergeometric functions whose arguments a, b, c are 1, 1/2, 1/3, ... or 0.[2]
  7. We give a basic introduction to the properties of Gauss hypergeometric functions, with an emphasis on the determination of the monodromy group of the Gaussian hyperegeo- metric equation.[3]
  8. Initially this document started as an informal introduction to Gauss hypergeometric functions for those who want to have a quick idea of some main facts on hypergeometric functions.[3]
  9. To confuse matters even more, the term "hypergeometric function" is less commonly used to mean closed form, and "hypergeometric series" is sometimes used to mean hypergeometric function.[4]
  10. The hypergeometric functions are solutions to the hypergeometric differential equation, which has a regular singular point at the origin.[4]
  11. Many functions of mathematical physics can be expressed as special cases of the hypergeometric functions.[4]
  12. We consider the asymptotic behavior of the Gauss hypergeometric function when several of the parameters a,b,c are large.[5]
  13. Computes the Gauss hypergeometric function 2F1(a,b;c;z) and its derivative for real z, z<1 by integrating the defining differential equation using the Matlab differential equation solver ode15i.[6]
  14. The major development of the theory of hypergeometric function was carried out by Gauss and published in his famous work of 1812.[7]
  15. Almost all of the elementary functions of Mathematics are either hypergeometric, ratios of hypergeometric functions or limiting cases of a hypergeometric series.[7]
  16. Two hypergeometric functions with the same argument z are contiguous if their parameters a, b and c differ by integers.[7]
  17. A contiguous relation between any three contiguous hypergeometric functions can be found by combining linearly a sequence of Gauss contiguous relations.[7]
  18. In this course we will study multivariate hypergeometric functions in the sense of Gelfand, Kapranov, and Zelevinsky (GKZ systems).[8]
  19. These functions generalize the classical hypergeometric functions of Gauss, Horn, Appell, and Lauricella.[8]
  20. We end with a brief discussion of the classication problem for rational hypergeometric functions.[8]
  21. For one-variable hypergeometric functions this interplay has been well understood for several decades.[8]
  22. Abstract The two most commonly used hypergeometric functions are the conflu- ent hypergeometric function and the Gauss hypergeometric function.[9]
  23. Except for specific situations, computing hypergeometric functions is difficult in practice.[9]
  24. (a)j (b)j zj j ! , which is also commonly denoted by M(a; b; z) and is itself often called the confluent hypergeometric function.[9]
  25. The function 2F1(a, b; c; z) is commonly denoted by F (a, b; c; z) and is also fre- quently called the Gauss hypergeometric function.[9]
  26. We nd that, for both the conuent and Gauss hypergeometric functions, there is no simple answer to the problem of their computation, and dierent methods are optimal for dierent parameter regimes.[10]
  27. 3.3 Writing the conuent hypergeometric function as a single fraction . . . . . .[10]
  28. 4.3 Writing the Gauss hypergeometric function as a single fraction .[10]
  29. The computation of the hypergeometric function pFq, a special function encountered in a variety of applications, is frequently sought.[10]
  30. Returns hyp2f1 scalar or ndarray The values of the gaussian hypergeometric function.[11]
  31. Using (41) and subordination property, we have thatBy adopting (13) and (64), we obtainApplying hypergeometric function (59), we obtain the upper bound for the case .[12]
  32. Recently, there has been a clear interest on Bessel and hypergeometric functions from the point of view of geometric function theory.[12]
  33. A hypergeometric function is the sum of a hypergeometric series, which is dened as follows.[13]
  34. When one of the numerator parameters ai equals N , where N is a nonnegative integer, the hypergeometric function is a polynomial in z (see below).[13]
  35. Sometimes the most general hypergeometric function pFq is called a generalized hypergeo- metric function.[13]
  36. For the hypergeometric function 2F1 we have an integral representation due to Euler: Theorem 1.[13]
  37. This generally speeds up evaluation by producing a hypergeometric function of lower order.[14]

소스

  1. ↑ 1.0 1.1 1.2 1.3 Numerical evaluation of the gauss hypergeometric
  2. ↑ 2.0 2.1 Hypergeometric function
  3. ↑ 3.0 3.1 Gauss’ hypergeometric function
  4. ↑ 4.0 4.1 4.2 Hypergeometric Function -- from Wolfram MathWorld
  5. ↑ Large parameter cases of the Gauss hypergeometric function
  6. ↑ Gauss Hypergeometric Function
  7. ↑ 7.0 7.1 7.2 7.3 Computers and mathematics with applications 61 (2011) 620–629
  8. ↑ 8.0 8.1 8.2 8.3 Three lectures on hypergeometric functions
  9. ↑ 9.0 9.1 9.2 9.3 Numer algor
  10. ↑ 10.0 10.1 10.2 10.3 Computation of
  11. ↑ scipy.special.hyp2f1 — SciPy v1.6.1 Reference Guide
  12. ↑ 12.0 12.1 (PDF) An integral representation of some hypergeometric functions
  13. ↑ 13.0 13.1 13.2 13.3 Hypergeometric functions
  14. ↑ Hypergeometric functions — mpmath 1.2.0 documentation


메타데이터

위키데이터

Spacy 패턴 목록

  • [{'LOWER': 'hypergeometric'}, {'LEMMA': 'function'}]
  • [{'LOWER': 'gaussian'}, {'LOWER': 'hypergeometric'}, {'LEMMA': 'function'}]
  • [{'LOWER': 'ordinary'}, {'LOWER': 'hypergeometric'}, {'LEMMA': 'function'}]
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