Rational Approximations to Generalized Hypergeometric Functions

Rational Hypergeometric Functions

Multivariate hypergeometric functions associated with toric varieties were introduced by Gel’fand, Kapranov and Zelevinsky. Singularities of such functions are discriminants, that is, divisors projectively dual to torus orbit closures. We show that most of these potential denominators never appear in rational hypergeometric functions. We conjecture that the denominator of any rational hypergeom...

Gauss Quadrature Approximations to Hypergeometric and Confluent Hypergeometric Functions

The Structure of Bivariate Rational Hypergeometric Functions

We describe the structure of all codimension-two lattice configurations A which admit a stable rational A-hypergeometric function, that is a rational function F all whose partial derivatives are non zero, and which is a solution of the A-hypergeometric system of partial differential equations defined by Gel’fand, Kapranov and Zelevinsky. We show, moreover, that all stable rational A-hypergeomet...

HYPERgeometric functions DIfferential REduction: MATHEMATICA based packages for differential reduction of generalized hypergeometric functions: Horn hypergeometric functions of two variables

The HYPERDIRE is a project devoted to creation of a set of Mathematica based programs for differential reduction of hypergeometric functions. The current version allow to manipulate with full set of Horn hypergeometric functions of two variables (34 functions). PROGRAM SUMMARY Title of program: HYPERDIRE Version: 1.0.0 Release: 1.0.0 Catalogue number : Program obtained from: https://sites.googl...

Towards all-order Laurent expansion of generalized hypergeometric functions around rational values of parameters

We prove the following theorems: 1) The Laurent expansions in ε of the Gauss hypergeometric functions 2F1(I1 + aε, I2 + bε; I3 + p q + cε; z), 2F1(I1 + p q + aε, I2 + p q + bε; I3+ p q + cε; z) and 2F1(I1+ p q +aε, I2+ bε; I3 + p q + cε; z), where I1, I2, I3, p, q are arbitrary integers, a, b, c are arbitrary numbers and ε is an infinitesimal parameter, are expressible in terms of multiple poly...