Elliptic Functions and Modular Forms

The theory of elliptic functions and modular forms is rich and storied, though it has a reputation for difficulty. In this textbook, the authors successfully bridge foundational concepts and advanced material. Following Weierstrass’s approach to elliptic functions, they also cover elliptic curves and complex multiplication. The sections on modular forms, which can be read independently, include discussions of Hecke operators and Dirichlet series. Special emphasis is placed on theta series, with some advanced results included. With detailed proofs and numerous exercises, this book is well-suited for self-study or use as a reference. A companion website provides videos and a discussion forum on the topic.

1 Elliptic functions.- 2 Geometry in the upper-half plane and the action of the modular group.- 3 Modular forms.- 4 The Hecke-Petersson theory.- 5 Theta series.

Max Koecher (born 1924) studied mathematics and physics at the University of Göttingen. He initially worked on modular forms of several variables, leaving his mark with a well-known principle bearing his name. Later on, he concentrated on Jordan algebras and in particular their connections with bounded symmetric domains. In 1970, he was appointed to Hans Petersson's chair at the University of Münster. He retired in 1989 and passed away shortly thereafter.

Aloys Krieg (born 1955) studied mathematics at the University of Münster. He was the last PhD student of Max Koecher. He has mainly worked on modular forms of several variables. In 1993, he was appointed to Paul Butzer's chair at RWTH Aachen University, where he served as Vice President for Education for 16 years. He retired in 2024.