Sharp Landen transformation inequalities for hypergeometric functions, with applications

We give examples of infinite order rational transformations that leave linear differential equations covariant. These examples are non-trivial yet simple enough illustrations of exact representations of the renormalization group. We first illustrate covariance properties on order-two linear differential operators associated with identities relating the same hypergeometric function with different rational pullbacks. These rational transformations are solutions of a differentially algebraic equation that already emerged in a paper by Casale on the Galoisian envelopes. We provide two new and more general results of the previous covariance by rational functions: a new Heun function example and a higher genus hypergeometric function example. We then focus on identities relating the same hypergeometric function with two different algebraic pullback transformations: such remarkable identities correspond to modular forms, the algebraic transformations being solution of another differentially algebraic Schwarzian equation that also emerged in Casale’s paper. Further, we show that the first differentially algebraic equation can be seen as a subcase of the last Schwarzian differential condition, the restriction corresponding to a factorization condition of some associated order-two linear differential operator. Finally, we also explore generalizations of these results, for instance, to , hypergeometric functions, and show that one just reduces to the previous cases through a Clausen identity. The question of the reduction of these Schwarzian conditions to modular correspondences remains an open question. In a hypergeometric framework the Schwarzian condition encapsulates all the modular forms and modular equations of the theory of elliptic curves, but these two conditions are actually richer than elliptic curves or hypergeometric functions, as can be seen on the Heun and higher genus example. This work is a strong incentive to develop more differentially algebraic symmetry analysis in physics.

Cubic modular equations in two variables

Chapter 1 - Classical theory of the [formula omitted

For primes p ≡ 1 (mod 12), we present an explicit relation between the traces of Frobenius on a family of elliptic curves with j-invariant 1728 / t and values of a particular 2 F 1 -hypergeometric function over F p . We also give a formula for traces of Hecke operators on spaces of cusp forms of weight k and level 1 in terms of the same traces of Frobenius. This leads to formulas for Ramanujan's T -function in terms of hypergeometric functions.

Mirror maps, modular relations and hypergeometric series II

The authors study certain monotoneity and convexity properties of the Gaussian hypergeometric function and those of the Euler gamma function.

Log-convexity and log-concavity of hypergeometric-like functions

Turán type inequalities for [formula omitted]-hypergeometric functions

Functional inequalities for the ratio of complete p-elliptic integrals

There are connections, already seen by Gauss himself, between his analytic work and the theory of quadratic forms. Some fragments from the early 1800s show that Gauss was familiar with the rudiments of a theory which eventually found its completion in Klein’s and Fricke’s work on modular forms. Both F. Klein and R. Fricke were deeply involved in the publication of Gauss’s work and had the opportunity to study Gauss’s fragments closely.

ABSTRACTAn earlier method for obtaining indefinite integrals of special function from the second-order linear equations which define them has been reformulated in terms of Riccati equations, which are nonlinear and first-order. For this application the nonlinearity is not a problem and the first-order property is a great advantage. Integrals can be derived using fragments of these Riccati equations and here only two specific fragment types are examined in detail. These fragments allow general integration formulas to be derived using quadrature. Other results will be presented separately. Results are presented here for Airy functions, Bessel functions, complete elliptic integrals, associated Legendre functions and Gauss hypergeometric functions. All results have been checked by differentiation using Mathematica.

There emerges different extended versions of Beta function and hypergeometric functions containing extra parameters. We obtain some properties of certain functions like extended Generalized Gauss hypergeometric functions, extended Confluent hypergeometric functions including transformation formulas, Mellin transformation for the generalized extended Gauss hypergeometric function in one, two and more variables.

При изучении арифметических свойств значений обобщенных гипергеометрических функций часто применяют известный в теории трансцендентных чисел метод Зигеля. Наиболее общие результаты в данной области были получены именно этим методом. Однако возможности метода Зигеля в случае гипергеометрических функций с иррациональнымипараметрами ограничены. Это связано с тем, что такие гипергеометрические функции не являются E-функциями, и по этой причине построить линейную приближающую форму свысоким порядком нуля с помощью принципа Дирихле здесь не удается. При рассмотрении задач, связанных с исследованием арифметической природы значений гипергеометрических функций с иррациональными параметрами, в некоторых случаях можно применить метод, основанный на эффективном построении линейной приближающей формы, но возможности этого метода также ограничены из-за того, что слишком общие эффективные конструкции отсутствуют. Трудности имеются также и в тех случаях, когда такие конструкции известны. Особенности этих конструкций таковы, что часто не удается реализовать арифметическую часть метода.Поэтому представляют интерес ситуации, когда можно провести требуемое исследование, опираясь на особые свойства конкретных гипергеометрических функций. Иногдаудается так подобрать параметры исследуемых функций, что можно преодолеть те трудности, которые возникают в общем случае. В настоящей работе рассматривается гипергеометрическая функция специального вида и ее производные. С помощью эффективной конструкции удалось не только доказать линейную независимость значений этих функций над некоторым мнимым квадратичным полем, но и получить соответствующий количественный результат в виде оценки модуля линейной формы от указанных значений.

A q-integral is a definite integral of a function of q having an expansion in non-negative powers of q for {|q|<1} (q-series). In his book on hypergeometric series, N. J. Fine [N. J. Fine, Basic Hypergeometric Series and Applications, Math. Surveys Monogr. 27, American Mathematical Society, Providence, 1988] explicitly evaluated three q-integrals. For example, he showed that \int_{0}^{e^{-\pi}}\prod_{n=1}^{\infty}\frac{(1-q^{2n})^{20}}{(1-q^{n})^{16}}% dq=\frac{1}{16}. In this paper, we prove a general theorem which allows us to determine a wide class of integrals of this type. This class includes the three q-integrals evaluated by Fine as well as some of those evaluated by L.-C. Zhang [L.-C. Zhang, Some q-integrals associated with modular forms, J. Math Anal. Appl. 150 1990, 264–273]. It also includes many new evaluations of q-integrals.

An exact expression is derived for the general finite‐part integral equation image over an inclined ellipticaldomain Ω. r denotes the distance of a point in Ω to the singular point \documentclass{article}\pagestyle{empty}\begin{document}$\left({x,y} \right).f = x_{^0 }^i y_0^j \sqrt {Z\left({x_{0,} y_0 }\right)}$\end{document} is a general function of the Cartesian co‐ordinates x0,y0. The boundary of the region Ω represents the equation Z(x0, y0)=O. These integrals appear during the numerical solution of plane crack problems in three‐dimensional elasticity where they are the dominant part of a hypersingular integral equation. The availability of exact expressions for the integrals with arbitrary integers i and j will increase the accuracy of the numerical results and, simultaneously, lead to quicker numerical results.The considered finite‐part integral can be expressed in closed form as function of complete elliptical integrals or Gauss hypergeometric functions, respectively.Formuias for special cases and some i, j values and their numerical verification are given in Appendices II and III.