The contact link just says <my_github_account_username>@gmail.com.
I'd love to look at some actual code if there's a github link?
http://htmlpreview.github.io/?https://github.com/aguaviva/Ph...
this one shows how to solve a double/n pendulum, which is something that is not explained in detail anywhere. So if you want to learn how constraints work that should get you up to speed!