Results 12 issues of Chris Birkbeck

This contains the definition of a congruence subgroup of `SL(2,Z)` and defines Gamma1, Gamma0 and full level subgroups. It also contains some basic results about them. --- [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

awaiting-review

The defines the notion of functions on the upper half plane being bounded at infinity and zero at infinity. This is required for #13250. --- [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

awaiting-review

This contains the basic definitions of modular forms and cusp forms together with some lemmas about mdifferentiability that are needed. --- - [x] depends on: #15009 [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

awaiting-author
t-analysis
t-differential-geometry

The contains the next set of results needed for #13500 . Note also the change of file name from pt1 since the name `circle_integral_transform` is no longer used (so the...

awaiting-author

--- [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

incomplete
t-analysis
too-late

Some files for defining modular forms and defining Eisenstein series. It also proves that Eisenstein series are modular forms. At the moment some are a complete mess, so still lots...

WIP
incomplete
merge-conflict
too-late

We show that Eisenstein Series are MDifferentiable - [x] depends on: #10377 - [x] depends on: #11244 --- [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

awaiting-author

We show Eisenstein series are modular forms. --- - [ ] depends on: #12456 [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

blocked-by-other-PR

Add some basic results about `ModularGroup.T` relating to slash invariant forms of level Gamma(N) and moving elements into verticalStrips. Needed for #12456 --- [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

awaiting-review
maintainer-merge

Add the q-expansion of the cotangent function that will be needed for Eisenstein series q-expansions. --- - [x] depends on: #12758 - [x] depends on: #12771 [![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)

awaiting-author