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17 q-Hypergeometric and Related FunctionsProperties

Β§17.6 Ο•12 Function

Contents
  1. Β§17.6(i) Special Values
  2. Β§17.6(ii) Ο•12 Transformations
  3. Β§17.6(iii) Contiguous Relations
  4. Β§17.6(iv) Differential Equations
  5. Β§17.6(v) Integral Representations
  6. Β§17.6(vi) Continued Fractions

Analytic Continuation

Note that for several of the equations below, the constraints are included to guarantee that the infinite series representation (17.4.1) of the Ο•12 functions converges. These equations can also be used as analytic continuation of these Ο•12 functions.

Β§17.6(i) Special Values

q-Gauss Sum

17.6.1 Ο•12⁑(a,bc;q,c/(a⁒b))=(c/a,c/b;q)∞(c,c/(a⁒b);q)∞,
|c|<|a⁒b|.

First q-Chu–Vandermonde Sum

Second q-Chu–Vandermonde Sum

Andrews–Askey Sum

17.6.4 Ο•12⁑(b2,b2/cc;q2,c⁒q/b2)=12⁒(b2,q;q2)∞(c,c⁒q/b2;q2)∞⁒((c/b;q)∞(b;q)∞+(βˆ’c/b;q)∞(βˆ’b;q)∞),
|c⁒q|<|b2|.

Related formulas are (17.7.3), (17.8.8) and

17.6.4_5 Ο•12⁑(b2,b2/cc⁒q2;q2,c⁒q3/b2)=12⁒b⁒(b2,q;q2)∞(c⁒q2,c⁒q/b2;q2)∞⁒((c⁒q/b;q)∞(b;q)βˆžβˆ’(βˆ’c⁒q/b;q)∞(βˆ’b;q)∞),
|c⁒q3|<|b2|.

For similar formulas see Verma and Jain (1983).

Bailey–Daum q-Kummer Sum

17.6.5 Ο•12⁑(a,ba⁒q/b;q,βˆ’q/b)=(βˆ’q;q)∞⁒(a⁒q,a⁒q2/b2;q2)∞(βˆ’q/b,a⁒q/b;q)∞,
|b|>|q|.

Β§17.6(ii) Ο•12 Transformations

Heine’s First Transformation

17.6.6 Ο•12⁑(a,bc;q,z)=(b,a⁒z;q)∞(c,z;q)βˆžβ’Ο•12⁑(c/b,za⁒z;q,b),
|z|<1,|b|<1.

Heine’s Second Tranformation

17.6.7 Ο•12⁑(a,bc;q,z)=(c/b,b⁒z;q)∞(c,z;q)βˆžβ’Ο•12⁑(a⁒b⁒z/c,bb⁒z;q,c/b),
|z|<1,|c|<|b|.

Heine’s Third Transformation

17.6.8 Ο•12⁑(a,bc;q,z)=(a⁒b⁒z/c;q)∞(z;q)βˆžβ’Ο•12⁑(c/a,c/bc;q,a⁒b⁒z/c),
|z|<1,|a⁒b⁒z|<|c|.

Fine’s First Transformation

17.6.9 Ο•12⁑(q,a⁒qb⁒q;q,z)=βˆ’(1βˆ’b)⁒(a⁒q/b)(1βˆ’(a⁒q/b))β’βˆ‘n=0∞(a⁒q,a⁒z⁒q/b;q)n⁒qn(a⁒z⁒q2/b;q)n+(a⁒q,a⁒z⁒q/b;q)∞(a⁒q/b;q)βˆžβ’Ο•12⁑(q,0b⁒q;q,z),
|z|<1.

Fine’s Second Transformation

17.6.10 (1βˆ’z)⁒ϕ12⁑(q,a⁒qb⁒q;q,z)=βˆ‘n=0∞(b/a;q)n⁒(βˆ’a⁒z)n⁒q(n2+n)/2(b⁒q,z⁒q;q)n,
|z|<1.

Fine’s Third Transformation

17.6.11 1βˆ’z1βˆ’b⁒ϕ12⁑(q,a⁒qb⁒q;q,z)=βˆ‘n=0∞(a⁒q;q)n⁒(a⁒z⁒q/b;q)2⁒n⁒bn(z⁒q,a⁒q/b;q)nβˆ’a⁒qβ’βˆ‘n=0∞(a⁒q;q)n⁒(a⁒z⁒q/b;q)2⁒n+1⁒(b⁒q)n(z⁒q;q)n⁒(a⁒q/b;q)n+1,
|z|<1,|b|<1.

Rogers–Fine Identity

17.6.12 (1βˆ’z)⁒ϕ12⁑(q,a⁒qb⁒q;q,z)=βˆ‘n=0∞(a⁒q,a⁒z⁒q/b;q)n(b⁒q,z⁒q;q)n⁒(1βˆ’a⁒z⁒q2⁒n+1)⁒(b⁒z)n⁒qn2,
|z|<1.

Nonterminating Form of the q-Vandermonde Sum

17.6.13 Ο•12⁑(a,b;c;q,q)+(q/c,a,b;q)∞(c/q,a⁒q/c,b⁒q/c;q)βˆžβ’Ο•12⁑(a⁒q/c,b⁒q/c;q2/c;q,q)=(q/c,a⁒b⁒q/c;q)∞(a⁒q/c,b⁒q/c;q)∞,
17.6.14 βˆ‘n=0∞(a;q)n⁒(b;q2)n⁒zn(q;q)n⁒(a⁒z⁒b;q2)n=(a⁒z,b⁒z;q2)∞(z,a⁒z⁒b;q2)βˆžβ’Ο•12⁑(a,bb⁒z;q2,z⁒q).

Three-Term Ο•12 Transformations

17.6.15 Ο•12⁑(a,bc;q,z)=(a⁒b⁒z/c,q/c;q)∞(a⁒z/c,q/a;q)βˆžβ’Ο•12⁑(c/a,c⁒q/(a⁒b⁒z)c⁒q/(a⁒z);q,b⁒q/c)βˆ’(b,q/c,c/a,a⁒z/q,q2/(a⁒z);q)∞(c/q,b⁒q/c,q/a,a⁒z/c,c⁒q/(a⁒z);q)βˆžβ’Ο•12⁑(a⁒q/c,b⁒q/cq2/c;q,z),
|z|<1,|b⁒q|<|c|.
17.6.16 Ο•12⁑(a,bc;q,z)=(b,c/a,a⁒z,q/(a⁒z);q)∞(c,b/a,z,q/z;q)βˆžβ’Ο•12⁑(a,a⁒q/ca⁒q/b;q,c⁒q/(a⁒b⁒z))+(a,c/b,b⁒z,q/(b⁒z);q)∞(c,a/b,z,q/z;q)βˆžβ’Ο•12⁑(b,b⁒q/cb⁒q/a;q,c⁒q/(a⁒b⁒z)),
|z|<1, |c⁒q|<|a⁒b⁒z|.

For a similar result for q-confluent hypergeometric functions see Morita (2013).

Β§17.6(iii) Contiguous Relations

Heine’s Contiguous Relations

17.6.17 Ο•12⁑(a,bc/q;q,z)βˆ’Ο•12⁑(a,bc;q,z) =c⁒z⁒(1βˆ’a)⁒(1βˆ’b)(qβˆ’c)⁒(1βˆ’c)⁒ϕ12⁑(a⁒q,b⁒qc⁒q;q,z),
17.6.18 Ο•12⁑(a⁒q,bc;q,z)βˆ’Ο•12⁑(a,bc;q,z) =a⁒z⁒1βˆ’b1βˆ’c⁒ϕ12⁑(a⁒q,b⁒qc⁒q;q,z),
17.6.19 Ο•12⁑(a⁒q,bc⁒q;q,z)βˆ’Ο•12⁑(a,bc;q,z) =a⁒z⁒(1βˆ’b)⁒(1βˆ’(c/a))(1βˆ’c)⁒(1βˆ’c⁒q)⁒ϕ12⁑(a⁒q,b⁒qc⁒q2;q,z),
17.6.20 Ο•12⁑(a⁒q,b/qc;q,z)βˆ’Ο•12⁑(a,bc;q,z) =a⁒z⁒(1βˆ’b/(a⁒q))1βˆ’c⁒ϕ12⁑(a⁒q,bc⁒q;q,z),
17.6.21 b⁒(1βˆ’a)⁒ϕ12⁑(a⁒q,bc;q,z)βˆ’a⁒(1βˆ’b)⁒ϕ12⁑(a,b⁒qc;q,z) =(bβˆ’a)⁒ϕ12⁑(a,bc;q,z),
17.6.22 a⁒(1βˆ’bc)⁒ϕ12⁑(a,b/qc;q,z)βˆ’b⁒(1βˆ’ac)⁒ϕ12⁑(a/q,bc;q,z) =(aβˆ’b)⁒(1βˆ’a⁒b⁒zc⁒q)⁒ϕ12⁑(a,bc;q,z),
17.6.23 q⁒(1βˆ’ac)⁒ϕ12⁑(a/q,bc;q,z)+(1βˆ’a)⁒(1βˆ’a⁒b⁒zc)⁒ϕ12⁑(a⁒q,bc;q,z)=(1+qβˆ’aβˆ’a⁒qc+a2⁒zcβˆ’a⁒b⁒zc)⁒ϕ12⁑(a,bc;q,z),
17.6.24 (1βˆ’c)⁒(qβˆ’c)⁒(a⁒b⁒zβˆ’c)⁒ϕ12⁑(a,bc/q;q,z)+z⁒(cβˆ’a)⁒(cβˆ’b)⁒ϕ12⁑(a,bc⁒q;q,z)=(cβˆ’1)⁒(c⁒(qβˆ’c)+z⁒(c⁒a+c⁒bβˆ’a⁒bβˆ’a⁒b⁒q))⁒ϕ12⁑(a,bc;q,z).

Β§17.6(iv) Differential Equations

Iterations of π’Ÿ

17.6.25 π’ŸqnΟ•12⁑(a,bc;q,z⁒d) =(a,b;q)n⁒dn(c;q)n⁒(1βˆ’q)n⁒ϕ12⁑(a⁒qn,b⁒qnc⁒qn;q,d⁒z),
17.6.26 π’Ÿqn((z;q)∞(a⁒b⁒z/c;q)βˆžβ’Ο•12⁑(a,bc;q,z)) =(c/a,c/b;q)n(c;q)n⁒(1βˆ’q)n⁒(a⁒bc)n⁒(z⁒qn;q)∞(a⁒b⁒z/c;q)βˆžβ’Ο•12⁑(a,bc⁒qn;q,z⁒qn).

q-Differential Equation

17.6.27 z⁒(cβˆ’a⁒b⁒q⁒z)β’π’Ÿq2Ο•12⁑(a,bc;q,z)+(1βˆ’c1βˆ’q+(1βˆ’a)⁒(1βˆ’b)βˆ’(1βˆ’a⁒b⁒q)1βˆ’q⁒z)Γ—π’ŸqΟ•12⁑(a,bc;q,z)βˆ’(1βˆ’a)⁒(1βˆ’b)(1βˆ’q)2⁒ϕ12⁑(a,bc;q,z)=0.

(17.6.27) reduces to the hypergeometric equation (15.10.1) with the substitutions aβ†’qa, bβ†’qb, cβ†’qc, followed by limqβ†’1βˆ’.

Β§17.6(v) Integral Representations

17.6.28 Ο•12⁑(qΞ±,qΞ²qΞ³;q,z) =Ξ“q⁑(Ξ³)Ξ“q⁑(Ξ²)⁒Γq⁑(Ξ³βˆ’Ξ²)⁒∫01tΞ²βˆ’1⁒(t⁒q;q)Ξ³βˆ’Ξ²βˆ’1(x⁒t;q)α⁒dqt.
17.6.29 Ο•12⁑(a,bc;q,z) =(βˆ’12⁒π⁒i)⁒(a,b;q)∞(q,c;q)βˆžβ’βˆ«βˆ’i⁒∞i⁒∞(q1+ΞΆ,c⁒qΞΆ;q)∞(a⁒qΞΆ,b⁒qΞΆ;q)βˆžβ’Ο€β’(βˆ’z)ΞΆsin⁑(π⁒΢)⁒dΞΆ,

where |z|<1, |ph⁑(βˆ’z)|<Ο€, and the contour of integration separates the poles of (q1+ΞΆ,c⁒qΞΆ;q)∞/sin⁑(π⁒΢) from those of 1/(a⁒qΞΆ,b⁒qΞΆ;q)∞, and the infimum of the distances of the poles from the contour is positive.

Β§17.6(vi) Continued Fractions

For continued-fraction representations of the Ο•12 function, see Cuyt et al. (2008, pp.Β 395–399).