## The hypergeometric equation and Ramanujan functions.(English)Zbl 1072.11052

There are 4 sections in this paper. The author gives the history of the Ramanujan functions and related topics. Ramanujan functions satisfy a system of nonlinear differential equations. This paper deals with both nonlinear systems satisfied by modular functions and identities between these functions and hypergeometric functions for a special choice of parameters. The author gives some examples related to these functions and analogues of the Ramanujan functions and nonlinear differential equations for them. He investigates a modular structure of solutions for nonlinear differential systems. He finds identities between the Ramanujan functions and hypergeometric functions. He also gives a solution of transcendence problems concerning nonlinear systems, which is given by the table explicitly.

### MSC:

 11J91 Transcendence theory of other special functions 11F03 Modular and automorphic functions 33C05 Classical hypergeometric functions, $${}_2F_1$$ 37F05 Dynamical systems involving relations and correspondences in one complex variable
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