I currently have two projects hosted on GitHub which may be of interest.

Linear Algebra Textbook

I have written/am writing a free linear algebra textbook. The book is aimed at math students who have already had some training in reading and writing proofs. I take a fields and vector spaces-first approach and try to help readers grapple with axioms.

Check out the textbook here.

An R Package: matrixmodp

In the course of writing the textbook (see above!), I wanted to be able to perform some basic calculations with matrices over finite (prime) fields. As I was learning R at the time, and as R didn’t have the capabilities I wanted, I wrote a package. You can find this package on CRAN or on GitHub.