9
Journal of Applied Mathematics and Stochastic Analysis, 10:3 (1997), 29%304. TRANSFORMATIONS OF CERTAIN GENERALIZED KAMPI DE FIRIET FUNCTIONS II HAROLD EXTON "Nyuggel", Lunabister, Dunrossness Shetland ZE2 9JH, United Kingdom (Received May, 1996; Revised October, 1996) The development of identities of multivariable hypergeometric functions is further extended based upon the methods of the previous study (H. Exton, J. Phys. A29 (1996), 357-363) these functions occur in various applications in the fields of physics and quantum chemistry. Key words: Hypergeometric Multivariable. AMS subject classifications: 33C50, 33C45, 33C90. 1. Introduction This study is a sequel to the work carried out by Exton [3] in which transformations of the Kamp de Friet functions of several variables, Karlsson [4], are obtained. This type of function has applications in mathematical physics and has previously been discussed by Niukkanen [5] and [6] and Srivastava [8-11] for example. The reader should consult these references for a detailed description of the applications of the type of function under consideration. It is denoted by FA.c:B: D I al’a2"’"aA;bl’2"’"bl’B;b2’l"’"b2’B;’";bn’l"’"bn’B; Cl, c2," Cc, dl, 2," dl, D; d2,1,’" ", d2, D;’" "; dn.1," dn.D; x 1, Xn I F A’C’bD I (a)’(b 1);...;(bn); (c):(dl);...;(dn); x 1, Xn I with series representation E ((a)’Xm)((bl)’l)" "((bn)’rnn)xl’"xnn (1 1) ((c), vrt)((d I ), vrt I i :(( - -n-1-( : .vrt-!’ in which the indices of summation run over all of the non-negative integers. The symbol (a) is a convenient contraction for the sequence of parameters al, a2, a n and the Pochhammer symbol (a, n), as usual, is given by Printed in the U.S.A. ()1997 by North Atlantic Science Publishing Company 297

CERTAINGENERALIZED KAMPI DE FIRIET FUNCTIONSKAMPIDEFIRIETFUNCTIONSII HAROLDEXTON "Nyuggel", Lunabister, Dunrossness Shetland ZE29JH, United Kingdom (Received May, 1996; Revised October,

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  • Journal of Applied Mathematics and Stochastic Analysis, 10:3 (1997), 29%304.

    TRANSFORMATIONS OF CERTAIN GENERALIZEDKAMPI DE FIRIET FUNCTIONS II

    HAROLD EXTON"Nyuggel", Lunabister, DunrossnessShetland ZE2 9JH, United Kingdom

    (Received May, 1996; Revised October, 1996)

    The development of identities of multivariable hypergeometric functions isfurther extended based upon the methods of the previous study (H. Exton,J. Phys. A29 (1996), 357-363) these functions occur in various applicationsin the fields of physics and quantum chemistry.

    Key words: Hypergeometric Multivariable.AMS subject classifications: 33C50, 33C45, 33C90.

    1. Introduction

    This study is a sequel to the work carried out by Exton [3] in which transformationsof the Kamp de Friet functions of several variables, Karlsson [4], are obtained.This type of function has applications in mathematical physics and has previouslybeen discussed by Niukkanen [5] and [6] and Srivastava [8-11] for example. Thereader should consult these references for a detailed description of the applications ofthe type of function under consideration. It is denoted by

    FA.c:B: D I al’a2"’"aA;bl’2"’"bl’B;b2’l"’"b2’B;’";bn’l"’"bn’B;Cl, c2," Cc, dl, 2," dl, D; d2,1,’" ", d2, D;’" "; dn.1," dn.D; x1, XnIFA’C’bD I (a)’(b1);...;(bn);

    (c):(dl);...;(dn);x1, XnI

    with series representation

    E ((a)’Xm)((bl)’l)" "((bn)’rnn)xl’"xnn (1 1)((c), vrt)((dI ), vrtI i :((--n-1-( : .vrt-!’in which the indices of summation run over all of the non-negative integers. Thesymbol (a) is a convenient contraction for the sequence of parameters al, a2, an andthe Pochhammer symbol (a, n), as usual, is given byPrinted in the U.S.A. ()1997 by North Atlantic Science Publishing Company 297

  • 298 HAROLD EXTON

    (a,n) r(a + n)/r(a) a(a + 1)...(a + n- 1); (a, 0) 1.Also, Em mI 2c...-1-rnn, etc., and any values of parameters for which any resultsdo not make sense are tacitly excluded. The above notation is discussed at greaterlength in Exton [2] and [3], for example.

    The following general result was presented in Exton [3] and is stated here forcompleteness:

    E ((a)’Em)((d)’Em)((Cl)’ml)((ql)’ml)((Zl)’2ml)

    ((Cn)’ mn)( qn), mn)( Zn), mn)(Xl, Yl ml"" "XnYn)mnpn rrtn bn rrtn ]Cn rrtn rrtl rrtn

    x FD:G: Q+ ZB + K

    (d) + Era" (ql)+ ml, (Zl)- 2ml;...;(qn + mn,(zn)+ 2ran;(g) -- Era: (bl) -- rrtl, (]1) - 2ml;’’ "; (bn) + ran, (]n) + 2ran;m1 mn((d), m)((q1), m1)((z1), ml).. "((qn), mn)((Zn), ran)X1 "Xn

    ((g), m)((bl), ml )((]1), ml)" "((bn, mn)((]Cn), ran)m1 !’’ "ran!

    FA: H: c + z + 1p + K

    (a)" (c1), (Zl)-- ml, ml;...; (Cn) (Zn)+ ran, ran; tYl"" Yn(h): (Pl), (]1) -t- ml;...; (Pn), (IOn) -Jr- ran;

    (1.3)The procedure now used consists of expressing the inner generalized Kamp6 de Ffrietfunctions in compact form, thus obtaining the transformations sought. Any questionsof convergence must be dealt with in each individual case as appropriate. The readeris referred to Exton [3] for more details of the above preliminaries.

    The following formulae are required in the subsequent analysis:

    1Fo[a; -;x] (1 x)-a, (the binomial theorem) (1.4)

    2Fl[a,b;c;x] (1 x)C-a-b2Fl[C-a,c-b;c;x], (1.5)

    FA’c’Io I (a):bl;,,;bn;(c)" -;,,; -; x,...,x A + 1FA[(a),Eb;(c);x], (1.6)F: O:

    --: (b1);,, ;(bn);-: (d1);,, ;(dn); Xl,...,Xnl-- BFD[(bl);(dl);Xl]...BFD[(bn);(dn);Xn],

    (1.7)

  • Transformations of Certain Generalized Kamp de Friet Functions II 299

    2Fl[a, n;c; 1] (c a, n)/(c, n), (Vandermonde’s theorem)

    3F2[a,b, -n;c,a+b-c-n+ 1;1]- [(c-a,n)(c-b,n)]/[(c,n)(c-a-b,n)],(Saalschfitz’s theorem)

    (1.8)

    (1.9)

    3F2[a, b, c; 1/2 + a/2 + b/2, 2c; 1]

    [r(1/2)r(c + 1/2)r(1/2 +a/2 +b/2)r(1/2-a/2-b/2 +c)]/

    and

    [r(1/2 + a/2)r(1/2 + b/2)r(1/2 a/2 + c)r(1/2 b/2 + c)](Watson’s theorem)

    (1.10)

    4F3[a/2, a/2 + 1/2, b -t- n, n;b/2, b/2 -- 1/2,1 + a; 1] (b a,n)/(b,n). (1.11)The results (1.4) and (1.8) through (1.11) are to be found in Slater [7], Appendix III.For the formulae (1.6) and (1.7), see Srivastava and Karlsson [12, page 39] and for(1.5), see Erdlyi [1, page 105]. In the following analysis, any expressions which aretrivial or which reduce immediately to transformations of one dimension are omitted.In order to save space, much of the detail of the working is left out, and the readershould consult Exton [3] if further clarification is desired.

    2. A Transformation Deduced from the Binomial Theorem

    In the general transformation (1.3), put D-G-Q-1, Z-B-K-0 and letx1 ...--xn-x and g-Eq. As a simple consequence of (1.6), we see that theinner Kamp$ de Friet function on the left takes the form

    d + Era: ql + ml;’-’; qn + ran; IF1" 1" 10 x,..., xEq + Em: ;...;

    2Fl[d +Em, Eq + Em;Eq + Era;x] (1 x)-d- Em (2.1)

    The expression (1.3) then becomes

    (1 x) dE ((a), Em)(d, Em)(ql n1).. "(qn, ran)

    ((Cl),ml)...(Cn),rnn)[XYl/(1 x)]ml...[xyn/(1 x)]mn((Pl)’ ml)’" "( (Pn), ran!’" "ran!

    E (d, Em)(ql rn1).. "(qn, tn)xEm

    FA" H" C + 1p(a): (el) ml;...; (Cn) ran;

    X

    (h):(Pl);...;(Pn);Yl"’"

  • 300 HAROLD EXTON

    If A- H- 0, the inner generalized Kamp de Friet function on the right may be sospecialized as to be summable by (1.8). After some algebra, we then have the result

    (1 x)-dF1" d:Cl, ql;...;cn,qn;

    1"21 Sq: Pl;’" "; Pn;1( 1),...,x/(x 1)

    d: Pl Cl, ql;’" "; Pn ca, qn;F1" 21 x,...,x (2.3)1- Eq: Pl;...; Pn;

    3. Three-term Transformation Deduced from (1.5)

    The inner series on the left of (1.3) can be expressed in closed form by means of (1.6)and (1.5) after suitably adjusting the parameters and variables. If D- Z- G- 1,A G Q B K O, xI =... xn x and g d- 1, this inner series becomes

    d + Ez: z + 2ml;...; zn + 2ran;1: lo

    d- 1 + Ez" -;...; -;

    2Fl[d + Era, Ez + 2Era; d- 1 + Era; x]

    (1 x)- 1 Ez- 2Era 2F1[ 1, d Ez 1 Era; d 1 + Era; x]

    (1 x)- 1 Ez 2Em[1 + (Ez d + 1 + Em)/(d 1 + Era)x]. (3.1)

    Hence, (1.3) takes the form

    (1 x) 1 EZF1.1" C + 2p

    Zl Zl 1. z zn 1.d: (c1), -,- -- ,...; (Cn) --,-- -- -, 4xyI 4xynd-l" (Pl) ;’"; (Pn) (1 x)2"" (1 x)2x(1 x)- 1 EZ(d z 1)/(d 1)

    Fl"l.c+2p

    z d -t-- l" (Pl);’"; (Pn)

    4xy

    (1__ x)2"’"

    E (d, m)(zl, m1).. .(Zn, m1):gEm

  • Transformations of Certain Generalized Kamp de Friet Functions H 301

    C + 2Fp[(Cl’Zl q ml, ml; (Pl); Yl]’"C + 2Fp[(Cn)’Zn -+ ran, mn;(Pn); Yn]"(.)

    The formulae (1.8) through (1.11) can then be used to sum the inner hypergeometricfunctions on the right of (3.2). In order to save space, the details of any working outare omitted, and the reader should see Exton [3].pectively"

    Zl Zl 1. Zn Znd’-,-+, "; 2, 12;F1" 1:21

    d-l" Pl ;’"; Pn

    (d r,z 1)/(d 1)1" .2

    The following results ensue, res-

    -4x -4x

    (1_ x)2"’" (1_ x)2

    Zl Zl 1. Zn Zn 1.Ez d + 2"--,-g- + - 2 2Ez d + 1" Pl ;’" "; Pn(1 x)1 + EZFI" 1" 22

    -4x

    (1 x)2"’"

    d" Zl, 1 + z1 Pl;" "; Zn, 1 + zn Pn; |"1

    --X,...,--;gd- 1" Pl ;" "; Pn (a.a)F1"a:32

    Zl Zl 1. Zn Zn 1.d" Cl ’-g"-g" + "" "; Cn’ 2 ,d 1" Pl, Cl + zl Pl + 1 ;...; Pn’ Cn q- Zn Pn q- 1;32x(d + Ez- 1)/(d- 1)F1" 1"

    (1-x (1 2

    Zl Zl 1. Zn Zn 1z d -+- 2 Cl -, -g- + - .Cn --, -g- 2;P.z-d + 1" pl,Cl + z1 -Pl + 1;...; Pn,Cl + zn Pn + 1;(1 x) 1 + EZFI" 1 "a2

    4x

    (l_x)2"’"

    d" z1, Pl Cl, 1 + z Pl ;’" "; Zn, Pn Cn, 1 + Zn Pn;d 1" Pl’ 1 + zl + c1 Pl;’" "; Pn’ 1 q- zn "-k cn Pn;

    (a.4)

    d" Cl, z1/2;...; Cn, Zn/2;d- 1" 2c1 ;...; 2Cn 4)2,x

    -4x

    "(1-x (l-x)2

  • 302 HAROLD EXTON

    x(d- Ez- 1)/(d- 1)F1" 1 "21

    Ez d + 2" Cl, z1/2, ;...; Cn, Zn/2

    Ez- d + 1" 2cI ;...; 2cn-4x

    (1 -x)2’’’’’4x

    (l-x)2

    (1 X) 1 + EzFl" 1" 21

    d/2 + 1/2"Zl/2, Zl/2 + 1/2-Cl;...;zn/2, zn/2 + 1/2-cn;d/2 1/2" cI + 1/2 ;...; cn + 1/2

    and

    F1" 1" 21

    d:a1/2,a1/2 + 1/2;...;an/2,an/2 + 1/2;

    d- 1: 1 + a1 ;...; 1 + an

    x(d- Ez- 1)/(d 1)F1: 1:21

    -4x

    (l-x)

    Ez d + 2" al /2, al /2 -t- 1/2;...;an, an/2 -t- 1/2;

    Ez d + 1" 1 + aI ;...; 1 + an4x 4x

    2(_x)’’" ’(_)

    (1 x)1 + EZFI" 1 "10 I -1d" z1 a1;.. .; zn an; |x,...,xJ, (3.6)d- 1" ;...;The right-hand side member of (3.6) can be simplified by appealing to (1.6) and(1.5). Hence,

    d:al/2, al/2 + 1/2;...;an, an/2, an/2 + 1/2;21 4x 4xF1 1"

    (1 x)2’’" (1 - ’-)d- 1" 1 + aI ;...; 1 + anx(d + Ez 1)/(d 1)r1" 1" 21

  • Transformations of Certain Generalized Kamp de Friet Functions H 303

    Ez-- d 4 2"a1/2,a1/2 4" 1/2;...;%/2, an/2 4" 1/2;4x 4x

    Ez d 4"1" l + a1 ;...; 14" an (l-x)2’’’’’(I-x)2

    (1 x)Ea[1 -(d 1 Ez 4" ra)/(d 1)x] (3.7)

    4. A Transformation of Higher Order

    This study is concluded by deducing a transformation of general order in which oneof the variables is restricted. As such, this type of expression does not possess asingle-variable analog.

    In the general result (1.3), put Q-Z-B-K-0 and let x,= -Xl-""-xn- 1" Utilizing an idea employed by Exton [2], we see that, as a consequence of(1.6), the inner Kamp de Friet function on the left reduces to unity. Hence

    E ((a)’rrt)((d)’m)((Cl)’rnl)’"((Cn)’rnn)(xlYl)ml’"(Xn- 1, Yn- 1)ran- 1

    ((h), m)((g), m)((p1), m1).. "((Pn), rrtn)ml !’’ "rrtn!

    X (-- yn[Xl 4"... 4" Xn- 1])mn

    "2 )"’E ((d), rrt)x?l.. "Xn T 1(_ Xe n-1((g), Srrt)rrtl !..

    X FA:H’C + 1p (a)" (c1), ml;...; (Cn) ran; Yl,’", Yn(h):(pl) ;’"; (Pn);

    (4.1)

    If A H 0, C P 1 and Yl =’-" Yn 1, the inner Kampfi de Ffiriet func-tion can be summed by means of (1.8). It then follows that

    FD: G: 11 / (d): Cl;...; Cn;(g)’Pl;’";Pn;

    FD:G:ll (d):P-Cl;’";Pn-Cn; Xl’"Xn-l --Xl--’"--Xn-1(g)’Pl;’";Pn;

    It is clear that this short list of transformation is far from complete.

    (4.2)

  • 304 HAROLD EXTON

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    Erdlyi, A., Higher Transcendental Functions, McGraw-Hill, New York 1953.Exton, H., Generating relations for Tratnik’s multivariable biorthogonal contin-uous Hahn polynomials, J. Math. Phys. 33 1992), 524-527.Exton, H., Transformations of certain generalized Kamp de Friet functions, J.Phys. A29 (1996), 357-363.Karlsson, P.W., Reduction of certain generalized Kamp de Friet functions,Math. Scand. 32 (1973), 265-268.Niukkanen, A.W., Generalized hypergeometric series NF(Xl,...,Xn) arising inphysical and quantum chemical applications, J. Phys. A16 (1983), 1813-1825.Niukkanen, A.W., Generalized reduction formulae for multiple hypergeometricseries NF(Xl,...,xn), J. Phys. A17 (1984), L16-L31.Slater, L.J., Generalized Hypergeometric Functions, Cambridge University Press1966.Srivastava, H.M., A class of generalized multiple hypergeometric series arisingin physical and quantum chemical applications, J. Phys. A18 (1985), L227-L234.Srivastava, H.M., Reduction and summation formulae for a certain class ofgeneralized multiple hypergeometric series arising in physical and quantumchemical applications, J. Phys. A18 (1985), 3079-3085.Srivastava, H.M., Neumann expansions for a certain class of generalized multi-ple hypergeometric series arising in physical and quantum chemical applica-tions, J. Phys. A20 (1987), 847-855.Srivastava, H.M., Some Clebsch-Gordon type linearization relations and otherpolynomial expansions associated with a class of generalized multiplehypergeometric series arising in physical and quantum chemical applications, J.Phys. A21 (1988), 4463-4470.Srivastava, H.M. and Karlsson, P.W., Multiple Gaussian Hypergeometric Series,Halsted Press, New York 1985.

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